func_code_string: #include <bits/stdc++.h>   using namespace std;   int fa[1010];   int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }   int main() {     int n, m;     scanf( %d%d , &n, &m);     if (m != n - 1) {       printf( no n );       return 0;     }     for (int i = 1; i <= n; i++) fa[i] = i;     for (int i = 1; i <= m; i++) {       int x, y;       scanf( %d%d , &x, &y);       int f1 = find(x), f2 = find(y);       if (f1 == f2) {         printf( no n );         return 0;       }       fa[f1] = f2;     }     printf( yes n );     return 0;   }   