#include <bits/stdc++.h>
using namespace std;

int main() {
    int n, p;
    cin >> n >> p;

    vector<int> a(n), b(n), c(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i] >> b[i] >> c[i];
    }

    static int dp[2][15050];
    memset(dp[0], 0x3f, sizeof(dp[0]));
    dp[0][0] = 0;

    for (int i = 0; i < n; i++) {
        int *dp0 = dp[i & 1];
        int *dp1 = dp[~i & 1];
        memset(dp1, 0x3f, sizeof(dp[0]));
        for (int j = 0; j <= 15000; j++) {
            dp1[j + 0] = min(dp1[j + 0], dp0[j] + a[i]);
            dp1[j + 1] = min(dp1[j + 1], dp0[j] + b[i]);
            dp1[j + 2] = min(dp1[j + 2], dp0[j] + c[i]);
            dp1[j + 3] = min(dp1[j + 3], dp0[j] + 1);
        }
    }

    double ans = 1.0 * dp[n & 1][p] / n;
    printf("%.20f\n", ans);
}