#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)

int main() {
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	
	int N, X, Q;
	cin >> N >> X >> Q;
	double E = 0;
	
	rep(i, 0, Q) {
		int M;
		cin >> M;
		
		set<int> S;
		bool findX = false;
		bool find2 = false;
		rep(j, 0, M) {
			int F;
			cin >> F;
			if (F == X) findX = true;
			else {
				if (S.count(F)) find2 = true;
				else S.insert(F);
			}
		}
		
		if (findX) E += 1;
		else if (find2) E += 0.5;
	}
	cout << fixed << setprecision(15) << E << '\n';
}