---
# System prepended metadata

title: SES0

---

<h1 class = "text-style">
    SES0
</h1>

<div style="color:green; font-size:150%;"><b>Challenge accepted</b></div>
---

>**By NPDang**

---
<h1 class = "text-style">
Bài tập    
</h1>

<font size="5" color="cyan"><b>800-Elo Problems</b></font>

:::spoiler <b>4A - Watermelon</b>
---
https://codeforces.com/problemset/problem/4/A
---
![image](https://hackmd.io/_uploads/H1JOkMArxx.png)
--- 
```c=    
#include<stdio.h> 
int main()
{
    int x;
    scanf("%d",&x);
    printf(x>2&&x%2==0?"YES":"NO");
}    
```
---

<h1>
    Giải thích
</h1>

---


:::

:::spoiler <b>231A - Team</b>
---
https://codeforces.com/problemset/problem/231/A
---
![image](https://hackmd.io/_uploads/SJ_eYKJrgg.png)
---
```cpp=
#include <iostream>
 
using namespace std;
 
int main()
{
    int n,br=0,count=0;
    bool b;
    cin>>n;
    for (int i=0; i<n;i++){
        cin>>b;
        br+=b;
        cin>>b;
        br+=b;
        cin>>b;
        br+=b;
        count+=(br>=2);
        br=0;
    }
    cout<<count;
}

```
---
:::

:::spoiler <b>71A - Way Too Long Words<b>

---
https://codeforces.com/problemset/problem/71/A
---

![image](https://hackmd.io/_uploads/ryXmKFyBlx.png)

---
    
```cpp=

#include <iostream>
#include <string>
using namespace std;

int main()
{
    string str;
    int n;
    cin>>n;
    for (size_t i = 0;i<n;i++)
    {
        cin>>str;
        if (str.length() > 10)
            cout<<str[0]<<str.length()-2<<str[str.length()-1]<<'\n';
        else
            cout<<str<<'\n';
    }
}
```

---

:::   

:::spoiler <b>A - Bit++</b>
---
codeforces.com/problemset/problem/282/A
---
![image](https://hackmd.io/_uploads/rJg2OtJSgx.png)

---
``` cpp=  
#include <iostream>
#include <string>

using namespace std;

int main()
{
    short n, x = 0;
    cin >> n;
    string str;
    cin.ignore();
    for (int i = 0; i < n; i++)
    {
        getline(cin, str);
        if (str.find("++") != string::npos)
            x++;
        else if (str.find("--") != string::npos)
            x--;
    }
    cout << x;
}    
```        
--- 
:::

:::spoiler 	158A - Next Round
---
https://codeforces.com/problemset/problem/158/A
---
![image](https://hackmd.io/_uploads/ByIZUklBgx.png)
---
```cpp=
#include <iostream>
using namespace std;

int main() {
    int n, k;
    cin>>n>>k;
    int scores[n]; 
    for (int i=0;i<n;i++){
        cin >> scores[i];
    }
    int gioihan=scores[k-1];
    int result=0; 
    for (int i = 0; i < n; i++){
        if (scores[i]>=gioihan&&scores[i]>0){
            result++;
        }
    }
    cout << result << endl;
    return 0;
}

```
---

:::

:::spoiler 50A - Domino piling
---
https://codeforces.com/problemset/problem/50/A
---
  ![image](https://hackmd.io/_uploads/S1qUd1xrgl.png)
---
```cpp=
#include <iostream>
using namespace std;

int main() {
    int a,b; cin>>a>>b;
    cout<<(a*b)/2;
    return 0;
}

```
---
:::

:::spoiler 263A - Beautiful Matrix
---
https://codeforces.com/problemset/problem/263/A
---
![image](https://hackmd.io/_uploads/S1WNCJxrle.png)
---
```cpp=    
#include <iostream>
#include <cmath>
using namespace std;

int main() {
    int num, result;
    for (int i = 1; i <= 5; i++)
    {
        for (int j=1; j<=5;j++){
            cin>>num;
            if (num){
                result=abs(3-i)+abs(3-j);
                cout<<result;
            }
        }
    } 
}  
``` 
---
:::

:::spoiler 112A - Petya and Strings
---
https://codeforces.com/problemset/problem/112/A
---
![image](https://hackmd.io/_uploads/SJhqzlerll.png)
--- 
```cpp=    
#include <iostream>
#include <string>
#include <cctype>
using namespace std;

int main() {
    string str,str2;
    cin>>str>>str2;
    for(int i =0; i<str.length();i++){
        if (tolower(str.at(i))!=tolower(str2.at(i)))
        {
            cout<<(tolower(str.at(i))>tolower(str2.at(i))?1:-1);
            return 0;
        }
        
    }
    cout<<0;
}  
```
---    
:::

:::spoiler 339A - Helpful Maths

---    
https://codeforces.com/problemset/problem/339/A
---
![image](https://hackmd.io/_uploads/SkljaWxBgl.png)
--- 
```cpp=
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    string str;
    cin>>str;
    int countnum;
    vector<int> num;
    for (int i = 0; i < 3; i++)
    {
        for (int j = 0; j<(countnum=count(str.begin(),str.end(),char(49+i))); j++)
        {
            num.push_back(i+1);
        }
    }
    for (int i=0; i< num.size();i++)
    {
        (i+1==num.size()?printf("%d",num.at(i)):printf("%d+",num.at(i)));
    }
    
}
```
---    
:::
    
:::spoiler 236A - Boy or Girl
---    
https://codeforces.com/problemset/problem/236/A
---
![image](https://hackmd.io/_uploads/HJxy6MgBll.png)
--- 
```cpp=    
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    vector<char> array(26,0);
    char ch;
    while ((ch=getchar())!=EOF)
    {
        if (ch<'a')
        {
            break;
        }
        
        array.at(ch-'a')|=1;
    }
    cout<<(count(array.begin(),array.end(),1)%2==0?"CHAT WITH HER!":"IGNORE HIM!");
}
```
---    

:::

:::spoiler 281A - Word Capitalization

---    
https://codeforces.com/problemset/problem/281/A
---
![image](https://hackmd.io/_uploads/BJcGHXeHgg.png)

--- 
```cpp=    
#include <iostream>
#include <cctype>
#include <string>
using namespace std;

int main() {
    string str;
    cin>>str;
    cout<<(str.at(0)<=90?str.at(0):str.at(0)-=32)<<str.substr(1);
}
```
---    
:::

:::spoiler 	791A - Bear and Big Brother
---
https://codeforces.com/problemset/problem/791/A
---
![image](https://hackmd.io/_uploads/rJEPkbWSxl.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int a,b;
    cin>>a>>b;
    for (int y = 1;; y++)
    {
        a*=3;
        b*=2;
        if (a>b)
        {
            cout<<y;
            break;
        }
    }
}
```
---    
:::
    
:::spoiler 266A - Stones on the Table
---
https://codeforces.com/problemset/problem/266/A
---
![image](https://hackmd.io/_uploads/S1EtQzbSxe.png)
---
```cpp=
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

int main() {
    int temp;
    cin >> temp;
    cin >> ws;
    vector<char> ch;
    for (int i = 0; i < temp; i++) {
        ch.push_back(getchar());
    }
    ch.resize(distance(ch.begin(),unique(ch.begin(),ch.begin()+temp)));
    cout<<temp-ch.size();

}

```
---
:::

:::spoiler 617A - Elephant
---
https://codeforces.com/problemset/problem/791/A
--- 
![image](https://hackmd.io/_uploads/Hyg-DZbSxg.png)
---
```cpp=    

#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int d;
    cin >> d;
    cout<<d/5+(d%5==0?0:1);
}  

```
---    
:::

:::spoiler 546A - Soldier and Bananas
---
https://codeforces.com/problemset/problem/546/A
---
![image](https://hackmd.io/_uploads/B1-9hWbBeg.png) 
--- 
```cpp=    
#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int n,k,w,res;
    cin >> k>> n>> w;
    res=n-k*((w+1) * floor(w/2)+(w%2==0?0:floor(w/2+1)));
    cout<<(res>=0?0:abs(res));
}    
```
---    
:::

:::spoiler	59A - Word
---
https://codeforces.com/problemset/problem/59/A
---
![image](https://hackmd.io/_uploads/HyBTxGWHlx.png)
--- 
```cpp=    
#include <iostream>
#include <cctype>
#include <algorithm>

using namespace std;

int main() {
    string str;
    cin>>str;
    int lowcount=count_if(str.begin(),str.end(),[](const char &ch){
        return islower(ch);});
    int uppcount=count_if(str.begin(),str.end(),[](const char &ch){
        return isupper(ch);});
    if(uppcount>lowcount){
        for_each(str.begin(),str.end(),[](const char &ch){
            cout<<char(toupper(ch));
        });
    }
    else{
        for_each(str.begin(),str.end(),[](const char &ch){
            cout<<char(tolower(ch));
        });
    }
}
```
---    
:::

:::spoiler 977A - Wrong Subtraction
---
https://codeforces.com/problemset/problem/977/A
---
![image](https://hackmd.io/_uploads/Skc27G-Hel.png)
--- 
```cpp=    
#include <iostream>
 
using namespace std;
 
int main() {
    int a,b;
    cin>>a>>b;
    for (int i = 0; i < b; i++)
    {
        a=(a%10==0?a/10:a-1);
    }
    cout<<a;
}
```
---    
:::
    
:::spoiler 	110A - Nearly Lucky Number
---
https://codeforces.com/problemset/problem/110/A
---
![image](https://hackmd.io/_uploads/S1diUMZSee.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int a;
    string str;
    cin>>str;
    a=count_if(str.begin(),str.end(),[](const char &ch){
        return ch=='7'||ch=='4';
    });
    cout<<(7==a||4==a?"YES":"NO");
}

```
---    
:::
    
:::spoiler 734A - Anton and Danik
---
https://codeforces.com/problemset/problem/734/A
---
![image](https://hackmd.io/_uploads/r1sPOM-Hex.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int a,length;
    cin>>length;
    string str;
    cin>>str;
    a=count(str.begin(),str.end(),'A');
    cout<<(a>(length-a)?"Anton":(a==length-a)?"Friendship":"Danik");
}
```
---    
:::
    
:::spoiler	41A - Translation
---
https://codeforces.com/problemset/problem/41/A
---
![image](https://hackmd.io/_uploads/HkVJqMbHee.png)

--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    string str, str2;
    cin>>str>>str2;
    reverse(str.begin(),str.end());
    cout<<(str==str2?"YES":"NO");
}    
```
---    
:::
    
:::spoiler 2094A - Trippi Troppi
---
https://codeforces.com/problemset/problem/2094/A
---
![image](https://hackmd.io/_uploads/rka9E4bSxg.png)
--- 
```cpp    	
#include <iostream>

using namespace std;

int main() {
    string str;
    int a;
    cin>>a;
    cin.ignore();
    for(int i=0; i<a;i++){
        getline(cin,str);
        cout<<str.at(0);
        for(int i=1; i<str.length();i++){
            if (str.at(i)==' ')
            {
                cout<<str.at(i+1);
            }
        }
        cout<<'\n';
    }
}

```
---    
:::
    
:::spoiler 677A - Vanya and Fence
---
https://codeforces.com/contest/677/problem/A
---
![image](https://hackmd.io/_uploads/HkCDiqzSle.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n,temp,h,count=0;
    cin>>n>>h;
    for (int i = 0; i < n; i++)
    {
        cin>>temp;
        count+=(temp>h?2:1);
    }
    cout<<count;   
}
```
---    
:::
    
:::spoiler 116A - Tram
---
https://codeforces.com/problemset/problem/116/A
---
![image](https://hackmd.io/_uploads/SkxAQozrel.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n,max=0, a,b,current=0;
    cin>>n;
    for (int i = 1; i < n; i++)
    {
        cin>>a;
        cin>>b;
        current=current-a+b;
        max=(current>max?current:max);
    }
    cout<<max;
}    

```
---    
:::

:::spoiler 	271A - Beautiful Year
---
https://codeforces.com/problemset/problem/271/A
---
![image](https://hackmd.io/_uploads/Hks5vsfBxg.png)  
--- 
```cpp=    
#include <iostream>
 
using namespace std;
 
int main() {
    int y;
    cin>>y;
    for (;;)
    {        
        y++;
        int temp1=y%10,temp2=y/100%10;
        if (temp2!=y/10%10&&temp1!=y/10%10&&temp2!=y/1000&&temp1!=temp2&&temp1!=y/1000&&y/10%10!=y/1000%10&&y/100%10!=temp1)
        {
            break;
        }
   
    }
    cout<<y; 
}    
```
---    
:::
    
:::spoiler	1030A - In Search of an Easy Problem
---
https://codeforces.com/problemset/problem/1030/A
---
![image](https://hackmd.io/_uploads/ByK3OsGSel.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n,temp;
    cin>>n;
    for (int i=0;i<n;i++)
    {        
        cin>>temp;
        if (temp)
        {
            cout<<"HARD";
            return 0;
        }
        
    }
    cout<<"EASY";
    return 0;    
}
```
---    
:::
    
:::spoiler 266B - Queue at the School
---
https://codeforces.com/problemset/problem/266/B
---
![image](https://hackmd.io/_uploads/HJuFnsGrll.png)

--- 
```cpp=    
#include <iostream>
#include <string>

using namespace std;

int main() {
    int n,t;
    cin>>n>>t;
    string str;
    cin>>str;
    for (int time = 0; time < t; ++time){
        for (int i = 0; i < n - 1; ++i){
            if (str[i]=='B'&&str[i+1]=='G') {
                swap(str[i], str[i + 1]);
                ++i;
            }
        }
    }
    cout << str;
    return 0;
}    
```
---    
:::

:::spoiler 467A - George and Accommodation
---
https://codeforces.com/problemset/problem/467/A
---
![image](https://hackmd.io/_uploads/HyX-CjzSex.png)

--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n, max, count=0, cur;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin >> cur >> max;
        if (max - cur >= 2)
        {
            count ++;
        }
    }
    cout << count;
    return 0;
}
```
---    
:::

:::spoiler 344A - Magnets
---
https://codeforces.com/problemset/problem/344/A
---
![image](https://hackmd.io/_uploads/S1Dbl3zSgg.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    string str,cur="";
    int n, count=0;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin>>str;
        if (cur != str)
        {
            cur = str;
            count ++;
        }
    }
    cout << count;
    return 0;
}    
```
---    
:::

:::spoiler 486A - Calculating Function
---
https://codeforces.com/problemset/problem/486/A
---
![image](https://hackmd.io/_uploads/SJZrm2zHel.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    long long n;
    cin >> n;
    cout << (n % 2 == 1?(n/2) *-1 - 1 : n/2);
    return 0;
}
```
---    
:::
    
:::spoiler	136A - Presents
---
https://codeforces.com/problemset/problem/136/A
---
![image](https://hackmd.io/_uploads/Syojr3zrex.png)    
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n;
    cin >> n;
    int f[n];
    for (int i = 0; i < n; i++)
    {
        int temp;
        cin >> temp;
        f[temp-1] = i + 1;
    }
    for (const int &i : f)
    {
        cout<<i<<' ';
    }  
    return 0;
}    
```
---    
:::
    
:::spoiler 200B - Drinks
---
https://codeforces.com/problemset/problem/200/B
---
 ![image](https://hackmd.io/_uploads/HJdduhzBlg.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    double result;
    short n;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        int temp;
        cin >> temp;
        result += temp;
    }
    cout<<result/n;    
}
```
---    
:::
    
:::spoiler 228A - Is your horseshoe on the other hoof?
---
https://codeforces.com/problemset/problem/228/A
---
![image](https://hackmd.io/_uploads/BkVrw3mBgg.png)
--- 
```cpp=    
#include <iostream>
#include <set>

using namespace std;

int main() {
    int temp = 0;
    set <int> arr;
    for (int i = 0; i < 4; i++)
    {
        cin >> temp;
        arr.insert(temp);
    }
    cout << 4 - arr.size();    
}    
```
---    
:::
    
:::spoiler 61A - Ultra-Fast Mathematician
---
https://codeforces.com/problemset/problem/61/A
---
![image](https://hackmd.io/_uploads/HJ7ET37rle.png) 
--- 
```cpp=    
#include <iostream>
#include <string>

using namespace std;

int main() {
    string str1, str2;
    cin >> str1 >> str2;
    for (int i = 0; i < str1.length(); i++)
    {
        if ( (str1[i] == '1'|| str2[i] == '1') && str1[i] != str2[i])
        {
            cout << '1';
        }
        else{
            cout << '0';
        }
    }
    
    return 0;
}    
```
---    
:::
                    
:::spoiler 	705A - Hulk
---
https://codeforces.com/problemset/problem/705/A
---
![image](https://hackmd.io/_uploads/ryzzJamSle.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int lay;
    cin >> lay;
    for (int i = 0; i < lay; i++)
    {
        if (i % 2 == 0){
            cout << "I hate ";
        }
        else{
            cout << "I love ";
        }
        if (i+1==lay)
        {
            cout << "it ";
        }
        else{
            cout << "that ";
        }
    }
    
    return 0;
}    
```
---    
:::
  
:::spoiler 1328A - Divisibility Problem
---
https://codeforces.com/problemset/problem/1328/A
---
![image](https://hackmd.io/_uploads/rJNHGpQHxg.png) 
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n, a, b;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin >> a >> b;
        if (a/b * b != a)
        {
            cout << (a/b + 1) * b - a << '\n';
        }
        else{
            cout << 0 << '\n';
        }        
    }
    
    return 0;
}    
```
---    
:::
    
:::spoiler 	520A - Pangram
---
https://codeforces.com/problemset/problem/520/A
---
![image](https://hackmd.io/_uploads/HkG-U6XBee.png)
--- 
```cpp=    
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    string str;
    int n;
    vector <int> alp(26);
    cin >> n >> str;
    if (str.length() < 26)
    {
        cout << "NO";
    }
    else{
        for (const char &ch : str){
            alp[tolower(ch) - 97] ++;        
        }
        if (count(alp.begin(), alp.end(), 0) != 0)
        {
            cout << "NO";
        }
        else cout << "YES";
    }
    return 0;
}    
```
---    
:::

:::spoiler 469A - I Wanna Be the Guy
---
https://codeforces.com/problemset/problem/469/A
---
![image](https://hackmd.io/_uploads/SyThtp7Hge.png)
--- 
```cpp=    
#include <iostream>
#include <set>
using namespace std;

int main() {
    set <int> lvs;
    int n;
    cin >> n;
    for (int i = 0; i < 2; ++i){
        int j;
        cin >> j;
        for (j; j>0; --j)
        {
            int temp;
            cin >> temp;
            lvs.insert(temp);
        }
    }
    cout << (lvs.size() == n ? "I become the guy." : "Oh, my keyboard!");
    return 0;
}    
```
---    
:::
    
:::spoiler 144A - Arrival of the General
---
https://codeforces.com/problemset/problem/144/A
---
![image](https://hackmd.io/_uploads/BkyIQ07Sll.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>
 
using namespace std;
 
int main() {
    int n;
    cin >> n;
    int arr[n];
    for (int i = 0; i < n; i++){
        int temp;
        cin >> temp;
        arr[i] = temp;
    }
    int *mp=max_element(arr, arr + n);
    int minVal = *min_element(arr, arr + n);
    int *np = arr + n - 1;
    while (*np != minVal) {
        --np;
    }
    if ( np < mp )
    {
        cout << distance(arr, mp) + distance(np, arr + n - 1) - 1; 
    }
    else{
        cout << distance(arr, mp) + distance(np, arr + n - 1);
    }
    
    return 0;
}    
```
---    
:::

:::spoiler 996A - Hit the Lottery
---
https://codeforces.com/problemset/problem/996/A
---
![image](https://hackmd.io/_uploads/BkOaFA7Hxl.png) 
--- 
```cpp=    
#include <iostream>
 
using namespace std;
 
int main() {
    int m, count = 0, opt[5] = {1, 5, 10, 20, 100};
    cin >> m;
    for (int i = 0; i < 5; i++){
        while (m >= opt[4 - i] && m > 0)
        {
            m -= opt[4 - i];
            count ++;
        }
    }
    cout << count;
    return 0;
}    
```
---    
:::

:::spoiler 148A - Isomina cure
---
https://codeforces.com/contest/148/problem/A
---
![image](https://hackmd.io/_uploads/ryoqYbtrgg.png)
--- 
```cpp=    
#include <iostream>

using namespace std;
 
int main() {
    int k, m, l, d, n, count = 0;
    cin >> k >> l >> m >> n >> d;
    for (int i = 1; i <= d; i ++){
        count += (i % k == 0 || i % l == 0 || i % m == 0 || i % n == 0);
    } 
    cout << count;
    return 0;
}    
```
---    
:::

:::spoiler 443A - Anton and Letters
---
https://codeforces.com/problemset/problem/443/A
---
![image](https://hackmd.io/_uploads/rJrCsbKSeg.png)
--- 
```cpp=    
#include <iostream>
#include <set>

using namespace std;
 
int main() {
    char ch;
    set<char> str;
    ch = getchar();
    while ((ch = getchar()) != EOF)
    {
        if (isalpha(ch)){
            str.insert(ch);
        }
    }
    cout << str.size();
    
    return 0;
}
```
---    
:::
    
:::spoiler 785A - Anton and Polyhedrons
---
https://codeforces.com/problemset/problem/785/A
---
![image](https://hackmd.io/_uploads/SyKoA-YSll.png)  
--- 
```cpp=    
#include <iostream>
#include <set>

using namespace std;
 
int main() {
    int n, count = 0;
    string str;
    cin >> n;
    cin.ignore();   
    for (int i = 0;i < n; i++){
        getline(cin, str);
        switch (str[0])
        {
        case 'C':
            count += 6;
            break;
        case 'T':
            count += 4;
            break;
        case 'O':
            count += 8;
            break;
        case 'D':
            count += 12;
            break;
        default:
            count += 20;
            break;
        }
    }
    cout << count;
    return 0;
}    
```
---    
:::

:::spoiler 268A - Games
---
https://codeforces.com/problemset/problem/268/A
---
![image](https://hackmd.io/_uploads/Sk6xzfKSgg.png)
--- 
```cpp=    
#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n, count = 0;
    cin >> n;
    vector<int> home(n), away(n);

    for (int i = 0; i < n; ++i)
        cin >> home[i] >> away[i];

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            if (i != j && home[i] == away[j])
                ++count;
        }
    }
    cout << count;
    return 0;
}    
```
---    
:::
    
:::spoiler 1335A - Candies and Two Sisters
---
https://codeforces.com/problemset/problem/1335/A
---
![image](https://hackmd.io/_uploads/ByfpuMYHxx.png)
 
--- 
```cpp=    
#include <iostream>
#include <cmath>

using namespace std;

int main() {
    long t, c, count = 0;
    cin >> t;
    for (int i = 0; i < t; i++)
    {
        cin >> c;
        cout << fixed << int(round(double(c)/2) - 1);
        if (i + 1 == t) continue;
        cout << '\n';
    }
    return 0;
}
```
---    
:::
    
:::spoiler 510A - Fox And Snake
---
https://codeforces.com/problemset/problem/510/A
---
![image](https://hackmd.io/_uploads/BJUHnMYBxl.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int a, b;
    cin >> a >> b;
    for (int i = 0; i < a; i++){
        switch (i % 4)
        {
            case 1:
                for (int i = 0; i < b - 1; i++)
                {
                    cout << '.';
                }
                cout << '#';
                break;
            case 3:
                cout << '#';
                for (int i = 0; i < b - 1; i++)
                {
                    cout << '.';
                }
                break;
            default:
                for (int i = 0; i < b; i++)
                {
                    cout << '#';
                }
                break;
        }
        if (i + 1 == a) continue;
        cout << '\n';
    }
    return 0;
}    
```
---    
:::
    
:::spoiler 141A - Amusing Joke
---
https://codeforces.com/problemset/problem/141/A
---
![image](https://hackmd.io/_uploads/SkdoRGFHxg.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int luabovaochuong[26] = {0};
    char ch;
    for (int i = 0; i < 2; i++)
    {
        while ((ch = getchar()) != '\n')
        {
            luabovaochuong[ch - 'A'] ++;
        }
    }
    
    while ((ch = getchar()) != EOF)
    {
        luabovaochuong[ch - 'A']--;
    }
    cout << (count(luabovaochuong, luabovaochuong + 26, 0) == 26? "YES" : "NO");
    
    return 0;
}    
```
---    
:::

:::spoiler 1352A - Sum of Round Numbers
---
https://codeforces.com/problemset/problem/1352/A
---
![image](https://hackmd.io/_uploads/SJrvMXFBex.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++){
        int temp;
        cin >> temp;
        vector <int> slices;
        int base = 1;
        while (temp > 0)
        {
            int di = temp % 10;
            if (di != 0) slices.push_back(di * base);
            temp /= 10;
            base *= 10;
        }
        cout << slices.size() << '\n';
        for (const int &i : slices){
            cout << i << ' ';
        }        
        cout << '\n';
    }
    return 0;
}
```
---    
:::
    
:::spoiler 723A - The New Year: Meeting Friends
---
https://codeforces.com/problemset/problem/723/A
---
![image](https://hackmd.io/_uploads/SygRN7Krlg.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int n[3];
    cin >> n[0];
    cin >> n[1];
    cin >> n[2];
    sort(n, n+3);
    cout << n[1]-n[0] + n[2]-n[1];
    return 0;
}
```
---    
:::
    
:::spoiler 1742A - Sum
---
https://codeforces.com/problemset/problem/1742/A
---
![image](https://hackmd.io/_uploads/SkQkiQYHle.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int s, n[3];
    cin >> s;
    for (int i = 0; i < s; i++){
        cin >> n[0] >> n[1] >> n[2];
        sort(n, n+3);
        cout << (n[1]+n[0]==n[2] ? "YES" : "NO");
        if (i + 1 == s) continue;
        cout << '\n';
    }
    return 0;
}    
```
---    
:::

:::spoiler 427A - Police Recruits
---
https://codeforces.com/problemset/problem/427/A
---
![image](https://hackmd.io/_uploads/SkSa2SqSxe.png)    
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int n, count = 0, temp, policers = 0;
    cin >> n;
    for (int i = 0; i < n; i ++){
        cin >> temp;
        if (policers == 0 && temp == -1) count ++;
        else policers += temp;
    }
    cout << count;
    return 0;
}    
```
---    
:::
    
:::spoiler 750A - New Year and Hurry
---
https://codeforces.com/problemset/problem/750/A
---
![image](https://hackmd.io/_uploads/By5Pw89rgg.png) 
--- 
```cpp=    
#include <iostream>


using namespace std;

int main() {
    int MAX = 240, a, b, base = 5, spent = 0;
    cin >> a >>b;
    int remain = MAX - b;
    for (int i = 1; i < a + 1; i++){
        spent += base*i;
        if (remain < spent){ 
            cout << i - 1;
            return 0;
        }
    }
    cout << a;
    return 0;
}
```
---    
:::    

:::spoiler 155A - I_love_\%username\%
---
https://codeforces.com/problemset/problem/155/A
---
![image](https://hackmd.io/_uploads/rk6KaIqSel.png)
--- 
```cpp=    
#include <iostream>


using namespace std;

int main() {
    int n, temp, max, min, count = 0;
    cin >> n >> max;
    min = max;
    for (int i  = 1; i < n; i++){
        cin >> temp;
        if (max < temp){
            count++;
            max = temp;
        }
        else if (min > temp){
            count++;
            min = temp;
        }
    }
    cout << count;
    return 0;
}    
```
---    
:::
    
:::spoiler 151A - Soft Drinking
---
https://codeforces.com/problemset/problem/151/A
---
![image](https://hackmd.io/_uploads/Sk3Vmv9Sxl.png)
--- 
```cpp=    
#include <iostream>
#include <set>

using namespace std;

int main() {
    int f, b, bl, c, cd, p, nb, np;
    cin >> f >> b >> bl >> c >> cd >> p >> nb >> np;
    set <int> amount;
    amount.insert(b * bl/nb);
    amount.insert(c * cd);
    amount.insert(p / np);
    cout << *amount.begin()/f;
    return 0;
}    
```
---    
:::

:::spoiler 1703A - YES or YES?
---
https://codeforces.com/problemset/problem/1703/A
---
![image](https://hackmd.io/_uploads/HyqsBw5Sxx.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n;
    cin >> n;
    char ch[4];
    for (int i = 0; i < n; i++){
        cin >> ch;
        if (tolower(ch[0]) != 'y' || tolower(ch[1]) != 'e' || tolower(ch[2]) != 's') cout << "NO";
        else cout << "YES";
        if (i + 1 == n) continue;
        cout << '\n';
    }
    return 0;
}    
```
---    
:::
    
:::spoiler 732A - Buy a Shovel
---
https://codeforces.com/problemset/problem/732/A
---
![image](https://hackmd.io/_uploads/B1PCODqHex.png)

--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int s, b, i = 1;
    cin >> s >> b;
    while ((s * i - b) % 10 != 0 && s * i % 10 != 0){
        i ++;
    }
    cout << i;
    return 0;
}
```
---    
:::

:::spoiler 630A - Again Twenty Five!
---
https://codeforces.com/problemset/problem/630/A
---
![image](https://hackmd.io/_uploads/BkUGcP5Sxe.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    cout << 25;
    return 0;
}    
```
---    
:::
    
:::spoiler 1154A - Restoring Three Numbers
---
https://codeforces.com/problemset/problem/1154/A
---
![image](https://hackmd.io/_uploads/Bk0fdnqBex.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int list[4];
    cin >> list[0] >> list[1] >> list[2] >> list[3];
    sort(list, list + 4);
    cout << list[3] - list[0] << ' ' << list[3] - list[1] << ' ' << list[3] - list[2];
    return 0;
}    
```
---    
:::
    
:::spoiler 581A - Vasya the Hipster
---
https://codeforces.com/problemset/problem/581/A
---
![image](https://hackmd.io/_uploads/H1Pd93cSel.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int a, b;
    cin >> a >> b;
    if (a > b) cout << b << ' ' << (a - b) /2;
    else cout << a <<' ' << (b - a) / 2;
    return 0;
}
```
---    
:::

:::spoiler 381A - Sereja and Dima
---
https://codeforces.com/problemset/problem/381/A
---
![image](https://hackmd.io/_uploads/Byjw6nqSex.png) 
--- 
```cpp=    
#include <iostream>
#include <deque>

using namespace std;

int main() {
    int n, temp;
    cin >> n;
    deque<int> list;
    for (int i = 0; i < n; i++)
    {
        cin >> temp;
        list.push_back(temp);
    }
    int sum1 = 0, sum2 = 0;
    for (int i = 0; i < n; i++)
    {
        temp = (list.front() > list.back() ? list.front() : list.back());
        (i % 2 == 0 ? sum1 : sum2) += temp;
        if (temp == list.front()) list.pop_front();
        else list.pop_back();
    }
    cout << sum1 << ' ' << sum2;
    
    return 0;
}    
```
---    
:::
    
:::spoiler 1669A - Division?
---
https://codeforces.com/problemset/problem/1669/A
---
![image](https://hackmd.io/_uploads/ryE1y6qBel.png)
 
--- 
```cpp=    
#include <iostream>
    
using namespace std;

int main() {
    int n, ranking;
    cin >> n;
    for (int i = 0; i < n; i++){
        cin >> ranking;
        cout << "Division ";
        if (ranking >= 1900) cout << "1";
        else if (ranking >= 1600) cout << '2';
        else if (ranking >= 1400) cout << "3";
        else cout << "4";
        
        if (i + 1 == n) continue;
        cout << '\n';        
    }
    
    return 0;
}
```
---    
:::
    
:::spoiler 1692A - Marathon
---
https://codeforces.com/problemset/problem/1692/A
---
![image](https://hackmd.io/_uploads/Hke3AqoBge.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int temp, n, list[4];
    cin >> n;
    for (int i = 0; i < n; i++){
        cin >> temp;
        list[0] = temp;
        for (int j = 1; j < 4; j++)
        {
            cin >> list[j];
        }
        sort(list, list + 4);
        cout << distance(find(list, list + 4, temp), list + 4) - 1;
        if (i + 1 == n) continue;
        cout <<'\n';
    }
    return 0;    
}
```
---    
:::
    
:::spoiler 1676A - Lucky?
---
https://codeforces.com/problemset/problem/1676/A
---
![image](https://hackmd.io/_uploads/r1arfsiSge.png) 
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n, sum1 = 0, sum2 = 0;
    cin >> n;
    cin.ignore();
    for (int i = 0; i < n; i++){
        sum1 += (_getchar_nolock() - '0');
        sum1 += (_getchar_nolock() - '0');
        sum1 += (_getchar_nolock() - '0');
        sum2 += (_getchar_nolock() - '0');
        sum2 += (_getchar_nolock() - '0');
        sum2 += (_getchar_nolock() - '0');
        if (sum1 == sum2) cout  << "YES";
        else cout << "NO";
        sum1 = sum2 = 0;
        if (i + 1 == n) continue;
        cout << '\n';
        _getchar_nolock();
    }
    return 0;    
}    
```
---    
:::

:::spoiler 1676A - Lucky?
---
https://codeforces.com/problemset/problem/1807/A
---
![image](https://hackmd.io/_uploads/ryXEBjoSex.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n, a, b, c;
    cin >> n;
    while (n--)
    {
        cin >> a >> b >> c;
        if (c == b + a) cout << '+';
        else cout << '-';
        if (n == 0) continue;
        cout << '\n';
    }
    return 0;    
}    
```
---    
:::
    
:::spoiler 1409A - Yet Another Two Integers Problem
---
https://codeforces.com/problemset/problem/1409/A
---
![image](https://hackmd.io/_uploads/rkPshjjrge.png) 
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n, a, b;
    cin >> n;
    while (n--){
        cin >> a >> b;
        if (a == b) cout << 0;

        else {
            cout << abs(b - a) / 10 + ( (b-a) % 10 != 0);
        }
        if (n == 0) continue;
        cout << '\n';
    }
    return 0;    
}    
```
---    
:::

:::spoiler 2065A - Skibidus and Amog'u
---
https://codeforces.com/problemset/problem/2065/A
---
![image](https://hackmd.io/_uploads/BknG1hiSll.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    string str;
    int n;
    cin >> n;
    while (n--){
        cin >> str;
        cout << str.substr(0, str.length() - 2) + 'i';
        if (n == 0) continue;
        cout << '\n';
    }
    return 0;    
}    
```
---    
:::
    
:::spoiler 1399A - Remove Smallest
---
https://codeforces.com/problemset/problem/1399/A
---
![image](https://hackmd.io/_uploads/HysJayhHxg.png)
--- 
```cpp=    
#include <iostream>
#include <vector>
#include <algorithm>

int main(){
    int t;
    std::cin >> t;
    while (t--) {
        int n;
        std::cin >> n;
        std::vector<int> a(n);
        for (int i = 0; i < n; ++i) {
            std::cin >> a[i];
        }
        std::sort(a.begin(), a.end());
        bool possible = true;
        for (int i = 0; i < n - 1; ++i) {
            if (a[i+1] - a[i] > 1) {
                possible = false;
                break;
            }
        }
        if (possible) {
            std::cout << "YES\n";
        } else {
            std::cout << "NO\n";
        }
    }

    return 0;
}    
```
---    
:::
    
:::spoiler 2114A - Square Year
---
https://codeforces.com/problemset/problem/2114/A
---
![image](https://hackmd.io/_uploads/ryicde2rle.png) 
--- 
```cpp=    
#include <iostream>
#include <cmath>

using namespace std;

int main(){
    int n, y;
    cin >> n;
    while (n--)
    {
        cin >> y;
        int res = int(sqrt(y));
        if (res * res == y) cout << res << ' ' << 0;
        else cout << -1;
        if (n == 0) continue;
        cout << '\n';
    }
    

    return 0;
}    
```
---    
:::

:::spoiler 2044A - Easy Problem
---
https://codeforces.com/problemset/problem/2044/A
---
![image](https://hackmd.io/_uploads/rJLU5xhrgl.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n, y;
    cin >> n;
    while (n--)
    {
        cin >> y;
        cout << y - 1;
        if (n == 0) continue;
        cout << '\n';
    }

    return 0;
}    
```
---    
:::

:::spoiler 2044A - Easy Problem
---
https://codeforces.com/contest/1985/problem/A
---
![image](https://hackmd.io/_uploads/rkYdBb2Hex.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n;
    string y;
    cin >> n;
    cin.ignore();
    while (n--)
    {
        getline(cin, y);
        cout << y[4] << y.substr(1,2) << ' ' << y[0] << y.substr(5,2);
        if (n == 0) continue;
        cout << '\n';
    }

    return 0;
}    
```
---    
:::
    
:::spoiler 1999A - A+B Again?
---
https://codeforces.com/problemset/problem/1999/A
---
![image](https://hackmd.io/_uploads/BJ4xdb2rxg.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n, y;
    cin >> n;
    cin.ignore();
    while (n--)
    {
        cin >> y;
        cout << y % 10 + y / 10;
        if (n == 0) continue;
        cout << '\n';
    }

    return 0;
}    
```
---    
:::

:::spoiler 32B - Borze
---
https://codeforces.com/problemset/problem/32/B
---
![image](https://hackmd.io/_uploads/rk2JTb2ree.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    char temp;
    while ((temp = _getchar_nolock()) != EOF)
    {
        if (temp == '.') cout << 0;
        else if (temp == '-')
        {
            temp = _getchar_nolock();
            if (temp == '.') cout << 1;
            else cout << 2;
        }
                
    }
    

    return 0;
}    
```
---    
:::
    
:::spoiler 1512A - Spy Detected!
---
https://codeforces.com/problemset/problem/1512/A
---
![image](https://hackmd.io/_uploads/S184EznBxx.png)  
--- 
```cpp=    
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    int n; cin >> n;
    while (n --){
        int size;
        cin >> size;
        vector<int> nums(size);
        for (int i = 0; i < size; i ++){
            cin >> nums[i];
        }
        vector<int> nums2 = nums;
        sort(nums.begin(),nums.end());
        if (nums[1] == nums.front()) cout << distance(nums2.begin(),find(nums2.begin(),nums2.end(), nums.back()) + 1);
        else cout << distance(nums2.begin(),find(nums2.begin(),nums2.end(), nums.front()) + 1);
        if (n == 0) continue;
        cout << '\n';
    }
    

    return 0;
}
```
---    
:::
    
:::spoiler 1791A - Codeforces Checking
---
https://codeforces.com/problemset/problem/1791/A
---
![image](https://hackmd.io/_uploads/SJQCrGnrle.png)  
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int n; cin >> n;
    string cf = "codeforces";
    cin.ignore();
    while (n --){
        char ch = _getchar_nolock();
        if (find(cf.begin(), cf.end(), ch) != cf.end()) cout << "YES";
        else cout << "NO";
        if (n == 0) continue;
        _getchar_nolock();
        cout << '\n';
    }
    

    return 0;
}   
```
---    
:::
    
:::spoiler 1760A - Medium Number
---
https://codeforces.com/problemset/problem/1760/A
---
![image](https://hackmd.io/_uploads/HJ9kXT3Sel.png)   
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int a, b, c, n;
    cin >> n;
    while (n--)
    {
        cin >> a >> b >> c;
        if ((a < b && b < c ) || (c < b && b < a)) cout << b;
        else if ((a < c && c < b) || (b < c && c < a)) cout << c;
        else cout << a;
        if (n == 0) continue;
        cout << '\n';
    }
    

    return 0;
}    
```
---    
:::
    
:::spoiler 1915A - Odd One Out
---
https://codeforces.com/problemset/problem/1915/A
---
![image](https://hackmd.io/_uploads/BJq6XpnHll.png)   
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int a, b, c, n;
    cin >> n;
    while (n--)
    {
        cin >> a >> b >> c;
        cout << (a ^= b ^= c);
        if (n == 0) continue;
        cout << '\n';
    }
    return 0;
}  
```
---    
:::
    
:::spoiler 758A - Holiday Of Equality
---
https://codeforces.com/problemset/problem/758/A
---
![image](https://hackmd.io/_uploads/B10orpnreg.png) 
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int temp, n, max = 0, sum = 0;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin >> temp;
        sum += temp;
        max = (max < temp ? temp : max);
    }
    cout << max * (n - 1) -(sum - max);
    

    return 0;
}    
```
---    
:::

:::spoiler
---
https://codeforces.com/problemset/problem/1560/A
---
![image](https://hackmd.io/_uploads/Sy3bppnreg.png)
--- 
```cpp=    
#include <iostream>
#include <vector>

using namespace std;

int main(){
    vector <int> list;
    int cur = 1;
    while (list.size() < 1000) { 
        if (cur % 3 != 0 && cur % 10 != 3) {
            list.push_back(cur);
        }
        cur++;
    }
    int n;
    cin >> n;
    while (n--) {
        int k;
        cin >> k;
        cout << list[k - 1] << '\n'; 
    }
    return 0;
}    
```
---    
:::
    
:::spoiler 472A - Design Tutorial: Learn from Math
---
https://codeforces.com/problemset/problem/472/A
---
![image](https://hackmd.io/_uploads/rJ2Jb03Sxl.png)    
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n;
    cin >> n;
    if (n % 2 == 0) cout << n - 8 << ' ' << 8;
    else cout << n - 9 << ' ' << 9;
    return 0;
}    
```
---    
:::
    
:::spoiler 1850A - To My Critics
---
https://codeforces.com/problemset/problem/1850/A
---
![image](https://hackmd.io/_uploads/Sk-xZyTBel.png)   
--- 
```cpp=    
#include <iostream>
#include <vector>

using namespace std;

int main(){
    int n, a, b, c;
    cin >> n;
    while (n--)
    {
        cin >> a >> b >> c;
        if (a + b >= 10 || b + c >= 10 || a + c >= 10) cout << "YES";
        else cout << "NO";
        if (n == 0) continue;
        cout << '\n';
    }
    
    return 0;
} 
```
---    
:::
    
:::spoiler 432A - Choosing Teams
---
https://codeforces.com/problemset/problem/432/A
---
![image](https://hackmd.io/_uploads/HJ-IDJprgg.png)   
--- 
```cpp=    
#include <iostream>
#include <vector>
    
using namespace std;

int main(){
    int n, t, count = 0;
    cin >> n >> t;
    vector<int> p(n);
    for (int i = 0; i < n; i ++){
        cin >> p[i];
    }
    for (const int & i : p){
        if (i + t <= 5) count++;        
    }
    cout << count / 3;
    return 0;
}
```
---    
:::

:::spoiler 490A - Team Olympiad
---
https://codeforces.com/problemset/problem/490/A
---
![image](https://hackmd.io/_uploads/r1mtxxpHex.png)
--- 
```cpp=
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    int n, t, count = 0;
    cin >> n;
    vector <int> PE, Code, Mat;
    for (int i = 1; i <= n; i++)
    {
        cin >> t;
        if (t == 1) Code.push_back(i);
        else if(t == 2) Mat.push_back(i);
        else PE.push_back(i);
    }
    int gmin = min({Code.size(),Mat.size(),PE.size()});
    cout << gmin << '\n';
    for (int i = 0; i < gmin; i++){
        cout << Code.at(i) << ' ' << Mat.at(i) << ' ' << PE.at(i);
        if (i + 1 == gmin) continue;
        cout << '\n';
    }
    
    return 0;
}    
```
---    
:::

:::spoiler 1899A - Game with Integers
---
https://codeforces.com/problemset/problem/1899/A
---
![image](https://hackmd.io/_uploads/rJTO5e6Bxl.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main(){
    int n, t;
    cin >> n;
    while(n--){
        cin >> t;
        cout << (t % 3 == 0 ? "Second": "First");
        if (n == 0) continue;
        cout << '\n';
    }
    
    return 0;
}    
```
---    
:::

:::spoiler 9A - Die Roll
---
https://codeforces.com/problemset/problem/9/A
---
![image](https://hackmd.io/_uploads/Bkz_6gTHgx.png)   
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int t, t2;
    cin >> t >> t2;
    if (t > t2){
        t ^= t2;
        t2 ^= t;
        t ^= t2;
    }
    int rem = 6 - t2 + 1;
    int g = __gcd(rem, 6);
    rem /= g;
    cout << rem << '/' << 6/g; 
    return 0;
}    
```
---    
:::
    
:::spoiler 2009A - Minimize!
---
https://codeforces.com/problemset/problem/2009/A
---
![image](https://hackmd.io/_uploads/ry4GJZaSgl.png)   
--- 
```cpp=    
#include <iostream>
    
using namespace std;

int main(){
    int n, a, b;
    cin >> n;
    while (n--)
    {
        cin >> a >> b;
        cout << -a + b;
        if (n == 0) continue;
        cout << '\n';
    }
    
    return 0;
}
```
---    
:::
    
:::spoiler 1873A - Short Sort
---
https://codeforces.com/problemset/problem/1873/A
---
![image](https://hackmd.io/_uploads/B1I_fbTHle.png)    
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int n, count = 2;
    string str;
    cin >> n;
    while (n--)
    {
        cin >> str;
        for (int i = 0; i < str.length(); i++){
            count -= (str.at(i) == i + 97); 
        }
        cout << (count > 1 ? "NO" : "YES");
        count = 2;
        if (n == 0) continue;
        cout << '\n';
    }
    
    return 0;
}
```
---    
:::
    
:::spoiler 1367A - Short Substrings
---
https://codeforces.com/problemset/problem/1367/A
---
![image](https://hackmd.io/_uploads/B1ZTE-aBxx.png)   
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int n;
    string str;
    cin >> n;
    while (n--)
    {
        cin >> str;
        for (int i = 0; i < str.length(); i++)
        {
            if (i % 2 == 0) cout << str.at(i);
        }
        cout << str.back();
        if (n == 0) continue;
        cout << '\n';
    }
    
    return 0;
}    
```
---    
:::

:::spoiler 1950A - Stair, Peak, or Neither?
---
https://codeforces.com/problemset/problem/1950/A
---
![image](https://hackmd.io/_uploads/S1jlIb6Bgg.png)
  
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int n, a, b, c;
    cin >> n;
    while (n--)
    {
        cin >> a >> b >> c;
        if (c > b && b > a) cout << "STAIR";
        else if (c < b && a < b) cout << "PEAK";
        else cout << "NONE";
        if (n == 0) continue;
        cout << '\n';
    }
    
    return 0;
}    
```
---    
:::

:::spoiler 703A - Mishka and Game
---
https://codeforces.com/problemset/problem/703/A
---
![image](https://hackmd.io/_uploads/SkxZuWTHgx.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int n, a, b, count1 = 0, count2 = 0;
    cin >> n;
    while (n--)
    {
        cin >> a >> b;
        count1 += (a > b);
        count2 += (b > a);
    }
    cout << (count1 > count2 ? "Mishka" : (count1 == count2 ? "Friendship is magic!^^" : "Chris"));
    return 0;
}   
```
---    
:::
    
:::spoiler 1829A - Love Story
---
https://codeforces.com/problemset/problem/1829/A
---
![image](https://hackmd.io/_uploads/HyHHKbpSgl.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main(){
    int n, count = 0;
    string str;
    const string cf = "codeforces";
    cin >> n;
    while (n--)
    {
        cin >> str;
        for (int i = 0; i < str.length(); i++){
            if (str.at(i) != cf.at(i)) count ++;
        }
        cout << count;
        count = 0;
        if (n == 0) continue;
        cout << '\n';
    }
    return 0;
}    
```
---    
:::

:::spoiler 1343B - Balanced Array
---
https://codeforces.com/problemset/problem/1343/B
---
![image](https://hackmd.io/_uploads/B1QnzM6Hll.png) 
--- 
```cpp=    
#include <iostream>
#include <vector>

int main() {
    int t;
    std::cin >> t;
    while (t--) {
        int n;
        std::cin >> n;

        if ((n / 2) % 2 != 0) {
            std::cout << "NO\n";
        } else {
            std::cout << "YES\n";
            std::vector<long long> a(n);

            long long sum_even = 0;
            for (int i = 0; i < n / 2; ++i) {
                a[i] = (i + 1) * 2;
                sum_even += a[i];
            }

            long long sum_odd = 0;
            for (int i = 0; i < n / 2 - 1; ++i) {
                a[n / 2 + i] = (i * 2) + 1;
                sum_odd += a[n / 2 + i];
            }

            a[n - 1] = sum_even - sum_odd;

            for (int i = 0; i < n; ++i) {
                std::cout << a[i] << (i == n - 1 ? "" : " ");
            }
            std::cout << "\n";
        }
    }
    return 0;
}    
```
---    
:::

:::spoiler 431A - Black Square
---
https://codeforces.com/problemset/problem/431/A
---
![image](https://hackmd.io/_uploads/BkPoSUpBxl.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int arr[4], sum = 0;
    cin >> arr[0] >> arr[1] >> arr[2] >> arr[3];
    cin.ignore();
    char ch;
    while ((ch = _getchar_nolock()) != EOF && ch != '\n')
    {
        sum += arr[ch - 49];
    }
    cout << sum;
    
    return 0;
}    
```
---    
:::
    
:::spoiler 80A - Panoramix's Prediction
---
https://codeforces.com/problemset/problem/80/A
---
![image](https://hackmd.io/_uploads/ry_pBPpBge.png)
--- 
```cpp=    
#include <iostream>
#include <vector>

using namespace std;

int main() {
    int a, n;
    cin >> a >> n;
    vector<bool> isPrime(n + 1, true);
    isPrime[0] = isPrime[1] = false;

    for (int p = 2; p * p <= n + 1; p++) {
        if (isPrime[p]) {
            for (int i = p * p; i <= n + 1; i += p) {
                isPrime[i] = false;
            }
        }
    }
    int nextPrime = -1;
    for (int i = a + 1; i <= n + 1; i++) {
        if (isPrime[i]) {
            nextPrime = i;
            break;
        }
    }
    if (nextPrime == n)
        cout << "YES";
    else
        cout << "NO";
    return 0;
}
    
```
---    
:::

:::spoiler 1800A - Is It a Cat?
---
https://codeforces.com/contest/80/problem/A
---
![image](https://hackmd.io/_uploads/SklP8vTHee.png)  
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n, length, currentcharacter;
    bool can = true;

    char meow[4]= {'m','e','o','w'};
    cin >> n;
    while (n--){
        cin >> length;
        currentcharacter = 0;
        string str;
        cin >> str;
        // duyet qu tung ky tu nek
        for (int i = 0; i < length; i ++){
            if (char(tolower(str.at(i))) != meow[currentcharacter]){
                currentcharacter++;
                if (i == 0|| currentcharacter > 3 || char(tolower(str.at(i))) != meow[currentcharacter]){
                    cout << "NO";
                    can = false;
                    break;
                }
            }
        }
        if (can && currentcharacter == 3) cout << "YES";
        else if (can) cout << "NO";
        can = true;
        currentcharacter = 0;
        if (n == 0) continue;
        cout << '\n';

    }
    return 0;
}    
```
---    
:::
    
:::spoiler 1857A - Array Coloring
---
https://codeforces.com/problemset/problem/1857/A
---
![image](https://hackmd.io/_uploads/HkQGsD6Bex.png)  
--- 
```cpp=    
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    int n;
    cin >> n;
    while (n--)
    {
        int size;
        vector<int> array;
        cin >> size;
        for (int i = 0; i < size; i++){
            int val;
            cin >> val;
            array.push_back(val);
        }
        int even = count_if(array.begin(), array.end(), [](const int &a){   
            return (a % 2 == 0);
        }), odd = size - even;
        if (odd % 2 == 0) cout << "YES";
        else cout << "NO";
        if (n == 0) continue;
        cout << '\n';
    }
    
}
    
```
---    
:::

:::spoiler 1829B - Blank Space
---
https://codeforces.com/problemset/problem/1829/B
---
![image](https://hackmd.io/_uploads/BkPv9y0Sel.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int n, count = 0, max = 0;
    cin >> n;
    while (n--)
    {
        int size;
        cin >> size;
        while (size --)
        {
            bool t;
            cin >> t;
            if (!t) count++;
            else if (t) {
                max = (count > max ? count : max);
                count = 0;
            }
        }
        max = (count > max ? count : max);
        cout << max;
        max = count = 0;
        if (n == 0) continue;
        cout << '\n';
    }
    
}
    
```
---    
:::

:::spoiler 1374A - Required Remainder
---
https://codeforces.com/problemset/problem/1374/A
---
![image](https://hackmd.io/_uploads/SkuXulRSxe.png)
--- 
```cpp=    
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    int n, a, b, n2;
    cin >> n;
    while (n--)
    {
        cin >> a >> b >> n2;
        if (n2 - n2 % a + b <= n2   ) {
			cout << n2 - n2 % a + b;
		} else {
			cout << n2 - n2 % a - (a - b);
		}
        if (n == 0) continue;
        cout << '\n';
    }
    
}
    
```
---    
:::

:::spoiler 1619A - Square String?
---
https://codeforces.com/problemset/problem/1619/A
---
![image](https://hackmd.io/_uploads/rkxIAlCHeg.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n, can;
    cin >> n;
    while (n--)
    {
        string str;
        cin >> str;
        if (str.length() % 2 == 0){
            for (int i = 0; i < str.length()/2; i++){
                if (str[i] != str[i + str.length() / 2]) {
                    can = false;
                    break;
                }
            }
        }
        else can = 0;
        if (can) cout << "YES";
        else cout << "NO";
        can = 1;
        if (n == 0) continue;
        cout << '\n';
    }
    
}
    
```
---    
:::

:::spoiler 1791C - Prepend and Append
---
https://codeforces.com/problemset/problem/1791/C
---
![image](https://hackmd.io/_uploads/BJbPzZ0ree.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int main() {
    int n;
    cin >> n;
    while (n--)
    {
        string str;
        int n2;
        cin >> n2 >> str;
        int count = n2;
        for (int i = 0; i < n2/2; i++){
            if (str.at(i) != str.at(n2 - i - 1)){
                count-= 2;
            }
            else break;
        }
        cout << count;
        if (n == 0) continue;
        cout << '\n';
    }
    
}
    
```
---    
:::

:::spoiler 1722A - Spell Check
---
https://codeforces.com/problemset/problem/1722/A
---
![image](https://hackmd.io/_uploads/rJwDB-0Sex.png)  
--- 
```cpp=    
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    int n;
    string T = "Trium";
    sort(T.begin(), T.end());
    cin >> n;
    while (n--)
    {
        string str;
        int n2;
        cin >> n2 >> str;
        sort(str.begin(), str.end());
        if (str.length() != 5) cout << "NO";
        else if (str == T) cout << "YES";
        else cout << "NO";
        if (n == 0) continue;
        cout << '\n';
    }
    
}

```
---    
:::

:::spoiler 1433A - Boring Apartments
---
https://codeforces.com/contest/1433/problem/A
---
![image](https://hackmd.io/_uploads/rkugh-0Hlg.png)
--- 
```cpp=    
#include <iostream>

using namespace std;

int checkdi (int n){
    int di = 0;
    while (n > 0)
    {
        n /= 10;
        di ++;
    }
    return di;
}

int acc(int di){
    if (di == 1) return 1;
    else return (di + acc(di - 1));
}


int main() {
    int n;
    cin >> n;
    while (n--)
    {
        int t;
        cin >> t;
        int di = checkdi(t), base = t % 10;
        di = acc(di);
        cout << (base - 1) * 10 + di;
        if (n == 0) continue;
        cout << '\n';
    }
    
}
```
---    
:::