func_code_string: #include <bits/stdc++.h>   using namespace std;   int find(int u[], int i) {     if (u[i] == i) {       return i;     }     return (u[i] = find(u, u[i]));   }   int main() {     int n, m;     cin >> n >> m;     if (n != m + 1) {       cout <<  no  << endl;       return 0;     }     int ufs[n];     for (int i = 0; i < n; i++) {       ufs[i] = i;     }     int a, b;     for (int i = 0; i < m; i++) {       cin >> a >> b;       int c = find(ufs, a - 1);       int d = find(ufs, b - 1);       if (c == d) {         cout <<  no  << endl;         return 0;       }       int m = min(c, d);       ufs[c] = m;       ufs[d] = m;     }     for (int i = 0; i < n; i++) {       if (find(ufs, i) != 0) {         cout <<  no  << endl;         return 0;       }     }     cout <<  yes  << endl;   }   