#include <stdio.h>
#include <vector>
using namespace std;

#define MAX_N 200000

struct Node {
  int subset;
  vector<int> edges;
};

Node nodes[MAX_N];

void addEdge(int a, int b) {
  nodes[a].edges.push_back(b);
  nodes[b].edges.push_back(a);
}
void dfs(int nodeIndex, int subset) {
  nodes[nodeIndex].subset = subset;

  for (int neighbour : nodes[nodeIndex].edges)
    if (nodes[neighbour].subset != subset)
      dfs(neighbour, subset);
}

int main() {
  FILE *fin, *fout;
  fin = fopen("dfs.in", "r");
  fout = fopen("dfs.out", "w");

  int n, m, i, a, b, noSubsets;
  fscanf(fin, "%d%d", &n, &m);
  for (i = 0; i < m; ++i) {
    fscanf(fin, "%d%d", &a, &b);
    addEdge(a, b);
  }

  noSubsets = 0;
  for (i = 0; i < n; ++i)
    if (nodes[i].subset == 0)
      dfs(i, ++noSubsets);

  fclose(fin);
  fclose(fout);
  return 0;
}