#include <iostream>

#include <vector>

#include <memory.h>

#include <iomanip>

using namespace std;

int main()

{

	// fast io

	ios::sync_with_stdio(false);

	cin.tie(nullptr);

	cout.tie(nullptr);

	int N, x, T, K;

	int P;

	int dp[23][1001];

	while (cin >> N >> x >> T >> K, N + x + T + K)

	{

		// calculate the tatal (maximum) price

		P = (++N * x) / (float)1.1 - (N * T);

		//cout << P << "\n";

		vector< pair<int, int> > pf;

		memset(dp, 0, sizeof(dp));

		int ans = 0;

		// store price and favour index

		// put each of the dim sums twice in the vector

		for (int i = 0; i < K; ++i)

		{

			int a, b = 0, tmp;

			cin >> a;

			for (int j = 0; j < N; ++j) cin >> tmp, b += tmp;

			pf.push_back({ a, b });

			pf.push_back({ a, b });

		}

		for (int k = 0; k < pf.size(); ++k)

		{

			auto& [price, favour] = pf[k];

			for (int i = N * 2; i > 0; --i) for (int j = P; j >= price; --j)

				dp[i][j] = max(dp[i][j], max(dp[i - 1][j], dp[i - 1][j - price] + favour));

		}

		for (int i = 0; i <= N * 2; ++i) ans = max(ans, dp[i][P]);

		cout << setprecision(2) << fixed << (double)ans / N << "\n";

	}

	return 0;

}