#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;

int main()
{
	cin.sync_with_stdio(false);
	int N, P;
	cin >> N >> P;
	vector<int> dp(P + 1, INF);
	dp[0] = 0;
	for (int i = 0, a[4]; i < N; i++) {
		cin >> a[0] >> a[1] >> a[2]; a[3] = 1;
		auto tdp = dp;
		fill(dp.begin(), dp.end(), INF);
		for (int j = 0; j <= 3; j++) {
			for (int k = 0; k <= P - j; k++) {
				if (tdp[k] != INF) {
					dp[k + j] = min(dp[k + j], tdp[k] + a[j]);
				}
			}
		}
	}
	cout << fixed << setprecision(6) << ((double)dp[P] / N) << endl;
	return 0;
}