为什么这么简单的题我竟然空下了！！！呃呃呃呃呃呃呃！

#include <iostream>

using namespace std;

int n, m, k, t, f, p[30001], rank[30001], a, b;

int find(int x) {
	if (x == p[x]) return x;
	else return p[x] = find(p[x]);
}

void un(int x, int y) {
	a = find(x);
	b = find(y);
	if (a == b)
		return;
	if (rank[a] > rank[b])
		p[b] = a;
	else {
		p[a] = b;
		if (rank[a] == rank[b])
			rank[b]++;
	}
}

int main() {
	int i, sum;
	while (cin >> m >> n && (m || n)) {
		for (i = 0; i < m; i++) {
			p[i] = i;
			rank[i] = 0;
		}
		for (i = 0; i < n; i++) {
			cin >> k;
			if (k >= 1)
				cin >> f;
			for (int j = 1; j < k; j++) {
				cin >> t;
				un(f, t);
			}
		}
		sum = 1;
		for (i = 1; i < m; i++) {
			if (find(i) == find(0))
				sum++;
		}
		cout << sum << endl;
	}
}

poj1611