#include <iostream>
#include <iomanip>
#include <cstring>
#include <algorithm> 
#include <queue>
#include <functional>
#include <map>
#include <vector>
#include <string>
using namespace std;
typedef long long ll;
const ll INF = 10000000000000;

ll dp[5005][15005];
ll n, p, a[5005][4];

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

    for (int i = 0; i <= n; i++){
        for (int j = 0; j <= p; 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 < 4; k++){
                if (k <= j) dp[i + 1][j] = min(dp[i + 1][j], dp[i][j - k]+a[i][k]);
            }
        }
    }

    double ans = (double)dp[n][p] / n;
    cout << ans << endl;

}