#include <bits/stdc++.h>
using namespace std;
int main () {
	int n, x, q;
	cin >> n >> x >> q;
	double ans = 0;
	set<int> s;
	while (q--) {
		int m;
		cin >> m;
		bool ex = false, d = false;
		s.clear();
		while (m--) {
			int a;
			cin >> a;
			ex = ex || (a == x);
			d = d || (s.find(a) != s.end());
			s.insert(a);
		}
		if (ex) {
			ans += 1;
		}else if (d) {
			ans += 0.5;
		}
	}
	cout << setprecision(20) << ans << endl;
}