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

int main(){
    int n, p; cin >> n >> p;
    int inf = 1e9;
    vector dp(p + 1, inf); dp[0] = 0;
    
    for(int k = 0; k < n; ++k){
        vector d(4, 1), ndp(p + 1, inf); swap(dp, ndp);
        for(int i = 0; i < 3; ++i) cin >> d[i];
        
        for(int i = 0; i <= 3; ++i){
            for(int j = 0; j <= p - i; ++j){
                dp[j + i] = min(dp[j + i], ndp[j] + d[i]);
            }
       }
    }
    
    printf("%.6f\n", dp[p] / double(n));
}