import ac_library.DSU;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.StreamTokenizer;

public class Main {
    public static void main(String[] args) throws IOException {
        StreamTokenizer in = new StreamTokenizer(new BufferedInputStream(System.in));
        in.nextToken();
        int n = (int) in.nval;
        in.nextToken();
        int m = (int) in.nval;
        DSU d = new DSU(n);
        for (int i = 0; i < m; i++) {
            in.nextToken();
            int u = (int) in.nval;
            in.nextToken();
            int v = (int) in.nval;
            d.merge(u, v);
        }
        int c = 0;
        for (int i = 0; i < n; i++) {
            if (d.leader(i) == i) c++;
        }
        System.out.println(c);
    }
}