func_code_string: #include <bits/stdc++.h>   using namespace std;   bool flag;   vector<vector<int> > g;   map<int, bool> used;   void dfs(int x, int last) {     used[x] = true;     for (auto to : g[x]) {       if (!used[to]) {         dfs(to, x);       } else {         if (last != to) {           flag = false;           return;         }       }     }     return;   }   int execute() {     int n, m;     cin >> n >> m;     g.resize(n + 1);     for (int i = 1; i <= m; i++) {       int x, y;       cin >> x >> y;       g[x].push_back(y);       g[y].push_back(x);     }     int cnt = 0;     for (int i = 1; i <= n; i++) {       if (!used[i]) {         flag = true;         dfs(i, i);         cnt += flag;       }     }     cout << cnt << endl;     return 0;   }   int TE = true;   bool mTest = false;   int main() {     ios_base::sync_with_stdio(false);     if (mTest) cin >> TE;     while (TE--) {       execute();     }     return 0;   }   