#include <bits/stdc++.h>

using namespace std;

int n, m;
vector <int> edges[100010];
bool visited[100010], f = false;

void DFS(int vertix, int prev) {
    visited[vertix] = true;
    for (int i = 0; i < edges[vertix].size(); i++) {
        if (!visited[edges[vertix][i]]) {
            DFS(edges[vertix][i], vertix);
        } else if (edges[vertix][i] != prev) {
            f = true;
        }
    }
}

int main()
{
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        edges[x].push_back(y), edges[y].push_back(x);
    }
    int res = 0;
    for (int i = 0; i < n; i++) {
        if (!visited[i]) {
            f = false;
            DFS(i, -1);
            if (!f)
                res++;
        }
    }
    cout << res;
}