---
# System prepended metadata

title: t13

---

## A
```cpp
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    
    unordered_set<string> s;
    string str;
    while(cin >> str) {
        if(s.count(str) == 0) cout << str << "\n";
        s.insert(str);
    }
    
    return 0;
}
```
## B
## C