Gincana

#include <bits/stdc++.h>
using namespace std;

int n, m;
vector<bool> visited;
vector<vector<int>> gr;

void dfs(int u) {
  visited[u] = true;
  for (int to : gr[u]) {
    if (!visited[to]) {
      dfs(to);
    }
  }
}

int main() {

  cin >> n >> m;

  visited.assign(n+1, false);
  gr.assign(n+1, vector<int>());

  int a, b;
  for (int i = 0; i < m; ++i) {
    cin >> a >> b;

    gr[a].push_back(b);
    gr[b].push_back(a);
  }

  int cnt = 0;
  for (int u = 1; u <= n; ++u) {
    if (!visited[u]) {
      ++cnt;
      dfs(u);
    }
  }

  cout << cnt << '\n';
}