func_code_string: #include <bits/stdc++.h>   using namespace std;   pair<long long int, long long int> p[300002];   int see(long long int a, long long int b, long long int c) {     for (long long int i = 0; i < c; i++) {       if (p[i].first == a || p[i].first == b || p[i].second == a ||           p[i].second == b)         continue;       if (b == -1)         return see(a, p[i].first, c) || see(a, p[i].second, c);       else         return 0;     }     return 1;   }   int main() {     long long int n, m, i;     cin >> n >> m;     for (i = 0; i < m; i++) cin >> p[i].first >> p[i].second;     if (see(p[0].first, -1, m) || see(p[0].second, -1, m))       cout <<  YES  << endl;     else       cout <<  NO  << endl;     return 0;   }   