#include <bits/stdc++.h>
using namespace std;
int n, m, cnt, flag;
vector<int> graph[100005];
bool vis[100005];
void dfs(int node, int parent) {
  vis[node] = 1;
  int x, u, v, i;
  cnt++;
  for (i = 0; i < graph[node].size(); i++) {
    v = graph[node][i];
    if (v == parent) continue;
    if (vis[v] == 1)
      flag = 1;
    else
      dfs(v, node);
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m;
  int i, j, k, u, v, x, sum = 0;
  for (i = 0; i < m; i++) {
    cin >> u >> v;
    graph[u].push_back(v);
    graph[v].push_back(u);
  }
  for (i = 1; i <= n; i++) {
    if (vis[i] == 0) {
      cnt = 0;
      flag = 0;
      dfs(i, 0);
      if (flag == 1)
        sum += cnt;
      else
        sum += (cnt - 1);
    }
  }
  cout << n - sum << endl;
}
