# OOP #1
## Bài tập cho điểm

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

long long a, b;

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    cin >> a >> b;
    cout << a + b;
    return 0;
}

## Phân số nhưng khó hơn

#include <bits/stdc++.h>
using namespace std;
#define int long long

typedef pair<int, int> pii;
typedef vector<pii> vii;



bool cmp(pii x, pii y){
    return ((1.0*x.first / (1.0*x.second)) < (1.0*y.first/(1.0*y.second)));
}

vii v;

signed main(){
    ios::sync_with_stdio(0); cin.tie(nullptr);
    int n;
    cin >> n;
    for(int i = 0; i < n; ++i){
        int x, y = 0;
        cin >> x;
        while(!y){
            cin >> y;
        }
        v.push_back(make_pair(x, y));
    }
    sort(v.begin(), v.end(), cmp);
    //cout << cmp(v[0], v[n - 1]) << '\n';
    cout << v[0].first << '/' << v[0].second << '\n';
    cout << v[n - 1].first << '/' << v[n - 1].second;

}

## Phân số nhưng khó hơn phiên bản cao cấp

#include <bits/stdc++.h>
using namespace std;
#define int long long

typedef pair<int, int> pii;
typedef vector<pii> vii;

void same(pii &x, pii &y){
    int ms = x.second * y.second / __gcd(x.second, y.second);

    x.first = x.first * (ms / x.second);
    y.first = y.first * (ms / y.second);
    x.second = ms;
    y.second = ms;
}

bool cmp(pii x, pii y){
    same(x, y);
    return x.first < y.first;
}

vii v;

signed main(){
    ios::sync_with_stdio(0); cin.tie(nullptr);
    int n, k;
    cin >> n >> k;
    for(int i = 0; i < n; ++i){
        int x, y;
        cin >> x >> y;
        v.push_back(make_pair(x, y));
    }
    sort(v.begin(), v.end(), cmp);
    if(!(k > n || k == 0)){
        cout << v[n - k].first << '/' << v[n - k].second << '\n';
        cout << v[k - 1].first << '/' << v[k - 1].second;
    }
}

## Tìm ngày kế tiếp

#include <bits/stdc++.h>
using namespace std;
#define int long long

class Date{
    private:
        int day, month, year;
    public:
        Date();
        Date(int d, int m, int y){
            this -> day = d;
            this -> month = m;
            this -> year = y;
        }
        void incYear(){
            ++year;
        }
        void incMonth(){
            ++month;
            if(month == 13){
                incYear();
                month = 1;
            }
        }
        void incDay(){
            ++day;
            if(((month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) && day > 31)
               || ((month == 4 || month == 6 || month == 9 || month == 11) && day > 30)
               || (month == 2 && ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) && day > 29)
               || (month == 2 && !((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) && day > 28)){
                incMonth();
                day = 1;
            }
        }
        void print(){
            cout << day << '/' << month << '/' << year;
        }
};

bool check(int d, int m, int y){
    if(y<=0) return 0;
    else if(m>12||m<=0) return 0;
    else {
        if(d<=0) return 0;
        else if((m==4||m==6||m==9||m==11)&&d>30) return 0;
        else if((m==1||m==3||m==5||m==7||m==8||m==10||m==12)&&d>31) return 0;
        else if(((y%4==0&&y%100!=0)||y%400==0)&&m==2&&d>29) return 0;
        else if(m==2&&!((y%4==0&&y%100!=0)||y%400==0)&&d>28) return 0;
        else return 1;
    }
}


signed main(){
    ios::sync_with_stdio(0); cin.tie(nullptr);
    int a, b, c;
    cin >> a >> b >> c;
    if(!check(a, b, c)){
        cout << "ERROR";
        return 0;
    }
    Date m(a, b, c);
    m.incDay();
    m.print();
}

## Anorld's cat map

#include <bits/stdc++.h>
using namespace std;

typedef vector<int> vi;


const int N = 1e3 + 3;
int n, k;

vector<vi> v, f;

pair<int, int> getPos(int x, int y){
    return make_pair((2 * x + y) % n, (x + y) % n);
}

void nextConfig(vector<vi> &v){
    vector<vi> ans(n, vi(n, 0));
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j){
            pair<int, int> pos = getPos(i, j);
            ans[pos.first][pos.second] = v[i][j];
        }
    }
    v = ans;
}

bool check(const vector<vi> &v){
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j){
            if(v[i][j] != v[0][0])
                return 0;
        }
    }
    return 1;
}

signed main(){
    ios::sync_with_stdio(0); cin.tie(nullptr);
    cin >> n;
    v.resize(n, vi(n, 0));
    f.resize(n, vi(n, 0));
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j){
            cin >> v[i][j];
            f[i][j] = v[i][j];
        }
    }
    if(check(v)){
        cout << 0;
        return 0;
    }
    do{
        nextConfig(v);
        ++k;
    }while(v != f);
    cout << k;
}

## Phân số khó hơn phiên bản max

#include<bits/stdc++.h>
using namespace std;

int n;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef vector<pii> vii;

bool cmp(pii x, pii y){
    return ((1.0*x.first / (1.0*x.second)) < (1.0*y.first/(1.0*y.second)));
}

bool cmpll(pll x, pll y){
    return ((1.0*x.first / (1.0*x.second)) == (1.0*y.first/(1.0*y.second)));
}

void mul(pll &x, pii y){
    x.first *= y.first;
    x.second *= y.second;
}


vii a;
vii res;
pll k;

signed main(){
    ios::sync_with_stdio(0); cin.tie(nullptr);
    cin >> n;
    for(int i = 0; i < n; ++i){
        int x, y;
        cin >> x >> y;
        a.push_back(make_pair(x, y));
    }
    sort(a.begin(), a.end(), cmp);
    cin >> k.first >> k.second;
    pair<long long, long long> ans;
    for(int i = 0; i < (1 << (n)); ++i){
        pair<long long, long long> tmp = make_pair(1, 1);
        for(int j = 0; j < n; ++j)
            if(i & (1 << j))
                mul(tmp, a[j]);
        if(cmpll(k, tmp)){
            for(int j = 0; j < n; ++j){
                if(i & (1 << j)){
                    cout << a[j].first << ' ' << a[j].second << '\n';
                }
            }
            return 0;
        }
    }
}