#include <fstream>
#include <vector>
#include <bitset>

using namespace std;
 
ifstream cin("dfs.in");
ofstream cout("dfs.out");

const int MAX = 100005;
bitset< MAX > used;

void dfs(int n, vector< vector< int > > &v) {
  vector< int > st(MAX, 0);
  int top = 0;
  st[++ top] = n;
  used[st[top]] = true;
  while(top) {
    for(auto x : v[st[top]]) {
      if(used[x])
        continue;
      used[x] = true;
      st[++top] = x;
      break;
    }
    top --;
  }
}

int main() {
  int n, m;
  cin >> n >> m;

  vector< vector< int > > v(n + 1);

  for(int i = 1; i <= m; i ++) {
    int x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
  }

  int sol = 0;
  for(int i = 1; i <= n; i ++) {
    if(used[i])
      continue;
    sol ++;
    dfs(i, v);
  }

  cout << sol << '\n';
}