neps512.cpp

/*
 * Contest : OBI 2013 - Fase 2
 * Problem : Famílias de Troia
 * Link    : https://neps.academy/br/exercise/512
 */

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

#define fastio ios::sync_with_stdio(0); cin.tie(0);
vector<vector<int>> adj;
vector<bool> visited;

void bfs(int no) {
  queue<int> fila;

  visited[no] = true;
  fila.push(no);

  while (!fila.empty()) {
    int atual = fila.front();
    fila.pop();

    for (auto v : adj[atual]) {
      if (!visited[v]) {
        fila.push(v);
        visited[v] = true;
      }
    }
  }
}

int main() {
  fastio

  int n, m;
  scanf("%i%i", &n, &m);
  adj.assign(n + 1, vector<int>());
  visited.assign(n + 1, false);

  int a, b;
  for (int i = 0; i < m; i++) {
    scanf("%i%i", &a, &b);

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

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

  printf("%i\n", cnt);

  return 0;
}