#include <atcoder/dsu>
#include <cstdio>

int main() {
    int n, m;
    if (scanf("%d %d", &n, &m) != 2) return 1;
    atcoder::dsu d(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        scanf("%d %d", &u, &v);
        d.merge(u, v);
    }
    printf("%d\n", (int)d.groups().size());
    return 0;
}