그룹 지정

#include <iostream>
#include <cstring>
using namespace std;
int gp[100001];
int find(int p){
    if (gp[p] == -1) return p;
    else return gp[p] = find(gp[p]);
}
void merge(int a, int b){
    a = find(a), b = find(b);//각 부모를 찾음
    if(a!=b) gp[b] = a; //부모가 다르다면
}
int main() {
    int N, M;
    cin >> N >> M;
    memset(gp, -1, sizeof(gp));
    for (int i = 0; i < M; i++){
        int a, b;
        cin >> a >> b;
        merge(a, b);
    }
    int ans = 0;
    for (int i = 1; i <= N; i++) if (gp[i] == -1) ans++;
    cout << ans << endl;
    return 0;
}