#include <iostream>
#include <iomanip>
#include <vector>
#include <map>
using namespace std;
using ll = long long;
int main() {
	int N, X, Q;cin >> N >>X >> Q;
	int a = 0;int b = 0;
	while (Q--) {
		int m;cin >> m;
		vector<int> f;
		map<int, int> ap;
		bool flg = false;
		while (m--) {
			int a;cin >> a;
			f.push_back(a);
			ap[a]++;
			if (a == X) flg = true;
		}
		if (flg) {
			a++;
			continue;
		}
		for (auto v : f) {
			if (ap[v] >= 2) {
				b++;break;
			}
		}
	}
	double ans = (double)a;
	ans += (double)b / (2.0);
	cout << setprecision(20) << ans << endl;
}