#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
const int INF = (int)1e9 + 1;

int n, p;
int dp[2][20010];
int score[5010][5];

int main(void) {
	cin >> n >> p;
	for (int i = 0; i < n; i++) {
		cin >> score[i][0] >> score[i][1] >> score[i][2];
		score[i][3] = 1;
	}

	for (int i = 0; i < 2; i++) {
		for (int j = 0; j < 20010; j++) {
			dp[i][j] = INF;
		}
	}
	dp[0][0] = 0;

	for (int i = 0; i < n; i++) {
		for (int j = 0; j <= p; j++) {
			for (int k = 0; k <= 3; k++) {
				if (j + k <= p) {
					dp[1][j + k] = min(dp[1][j + k], dp[0][j] + score[i][k]);
				}
			}
		}
		for (int j = 0; j <= p; j++) {
			dp[0][j] = dp[1][j];
			dp[1][j] = INF;
		}
	}

	cout << fixed << setprecision(9) << (double)dp[0][p] / (double)n << endl;
	return 0;
}