#include "bits/stdc++.h"

using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;
int dp[2][15001];
int a[5000][4];
int main() {
	int N, P;
	cin >> N >> P;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < 3; j++) cin >> a[i][j];
		a[i][3] = 1;
	}
	fill((int*)dp, (int*)(dp + 2), 1 << 30);
	dp[0][0] = 0;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j <= min(3 * i, P); j++) {
			if (dp[i & 1][j] == 1 << 30) continue;
			for (int k = 0; k <= 3; k++) {
				if (j + k <= P) dp[(i + 1) & 1][j + k] = min(dp[(i + 1) & 1][j + k], dp[i & 1][j] + a[i][k]);
			}
		}
		for (int j = 0; j <= P; j++) dp[i & 1][j] = 1 << 30;
	}
	printf("%.10lf\n", dp[N & 1][P] * 1.0 / N);
}