func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<long long> v[100000 + 1];   long long n, m;   long long taken[100000 + 1];   map<int, int> v2;   int check = 0, sum;   void bfs() {     queue<long long> q;     long long j, x, y;     for (int i = 1; i <= n; i++) {       if (taken[i] == 0) {         q.push(i);         check = 0;         while (!q.empty()) {           x = q.front();           q.pop();           v2[x] = 1;           for (j = 0; j < v[x].size(); j++) {             y = v[x][j];             if (taken[y] == 0) {               q.push(y);               taken[y] = 1;             } else if (taken[y] == 1 && v2[y] == 0) {               check = 1;             }           }         }         if (check == 0) {           sum = sum + 1;         }       }     }   }   int main() {     long long i, x, y;     cin >> n >> m;     for (i = 1; i <= m; i++) {       cin >> x >> y;       v[x].push_back(y);       v[y].push_back(x);     }     sum = 0;     bfs();     cout << sum <<   n ;   }   