#include <fstream>
#include <vector>
using namespace std;

vector <int> v[100005];
bool viz[100005];
int solutie;

void DFS (int x) {
    viz[x] = 1;
    vector <int> :: iterator it;
    for (it = v[x].begin(); it != v[x].end(); ++it) {
        if (!viz[*it]) DFS(*it);
    }

}
int main()
{
    ifstream f("dfs.in");
    ofstream g("dfs.out");
    int n, m, x;
    f >> n >> m;
    for (int i = 1; i <= m; ++i) {
        int a, b;
        f >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    DFS(x);
    vector <int> :: iterator it;
    for (int i = 1; i <= n; ++i)
        if (!viz[i]) DFS(i), ++solutie;
    g << solutie << "\n";
    return 0;
}