#include <iostream>
#include <algorithm>
#include <cstdio>

using namespace std;

typedef long long ll;

int N, P;

int a[5005][4];

int dp[2][15005];

int main()
{
    cin >> N >> P;

    for (int i = 0; i < N; ++i) {
        for (int j = 0; j <= 2; ++j) {
            cin >> a[i][j];
        }
        a[i][3] = 1;
    }

    for (int i = 0; i < 2; ++i) for (int j = 0; j <= P; ++j) dp[i][j] = 1e9;
    dp[0][0] = 0;

    for (int i = 0; i < N; ++i) {
        for (int j = P; j >= 0; --j) {
            for (int k = 0; k <= 3; ++k) {
                if (j - k >= 0) {
                    dp[(i + 1) & 1][j] = min(dp[(i + 1) & 1][j], dp[i & 1][j - k] + a[i][k]);
                }
            }
        }

        for (int j = 0; j <= P; ++j) dp[(i & 1)][j] = 1e9;
    }

    printf("%.6f\n", (double)dp[(N & 1)][P] / N);
}