func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, ans, fa[100001];   bool mark[100001];   int find(int x) {     if (x == fa[x]) return x;     return fa[x] = find(fa[x]);   }   int main() {     cin >> n >> m;     for (int i = 1; i <= n; i++) fa[i] = i;     for (int i = 1; i <= m; i++) {       int x, y;       cin >> x >> y;       int fx = find(x), fy = find(y);       if (fx != fy) {         fa[fx] = fy;         if (mark[fx] || mark[x] || mark[fy] || mark[y])           mark[fx] = mark[x] = mark[fy] = mark[y] = 1;       } else         mark[fx] = mark[x] = mark[fy] = mark[y] = 1;     }     for (int i = 1; i <= n; i++)       if (find(i) == i && !mark[i]) ans++;     cout << ans << endl;     return 0;   }   