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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int main() {
  5.     int n, m;
  6.     cin >> n >> m;
  7.     int ms[n][n] = {};
  8.     for (int i = 0; i < m; i++) {
  9.         int a, b;
  10.         cin >> a >> b;
  11.         a--; b--;  
  12.         if (ms[a][b] == 1 || ms[b][a] == 1) {
  13.             cout << "NO" << endl;
  14.             return 0;  
  15.         }
  16.         ms[a][b] = 1;
  17.         ms[b][a] = 1;
  18.     }
  19.     cout << "YES" << endl;
  20.  
  21.     return 0;
  22. }
Success #stdin #stdout 0.01s 5276KB
comments (?)
stdin
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5 3
2 5
3 1
3 2
stdout
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YES
https://ideone.com/6seU5F
language:
C++14 (gcc 8.3)
created:
9 days ago
visibility:
public

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