#include <iostream>
#include <algorithm>
#include <stdio.h>
using namespace std;
typedef long double ld;
const int INF = 1 << 29;
int N, P;
int dp1[15010],  dp2[15010];
int main(void) {
	cin >> N >> P;
	for (int p = 0; p <= P; ++p) dp1[p] = dp2[p] = INF;
	dp1[0] = 0;
	for (int n = 0; n < N; ++n) {
		int nums[4]; cin >> nums[0] >> nums[1] >> nums[2]; nums[3] = 1;
		for (int p = 0; p <= P; ++p) {
			if (dp1[p] == INF) continue;
			for (int i = 0; i < 4; ++i) {
				dp2[p + i] = min(dp2[p + i], dp1[p] + nums[i]);
			}
		}
		for (int i = 0; i <= P; ++i) {
			dp1[i] = dp2[i];
			dp2[i] = INF;
		}
	}
	printf("%.15Lf\n", (ld)dp1[P] / (ld)N);
	return 0;
}