#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <functional>
#include <queue>
#include <iostream>
#include <string.h>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <cstdint>
#include <climits>
#include <unordered_set>
#include <sstream>

using namespace std;

#define ll long long int
#define pll pair<double,ll>

vector<ll> dp[4];

int main()
{
    int n, p;
    cin >> n >> p;
    vector<int> as[4];
    for(int i = 0;i < 4;i++)
    {
        as[i].resize(n);
    }
    for(int i = 0;i < n;i++)
    {
        cin >> as[0][i] >> as[1][i] >> as[2][i];
        as[3][i] = 1;
    }
    for(int i = 0;i < n+1;i++)
    {
        dp[i].resize(p+1);
        fill(dp[i].begin(), dp[i].end(), (ll)1e12);
    }
    fill(dp[0].begin(), dp[0].end(), 0);
    for(int i = 0;i < n;i++)
    {
        for(int w = 0; w < 4;w++)
        {
            ll c = as[w][i];
            for(int j = w;j <= p;j++)
            {
                dp[i+1][j-w] = min(dp[i+1][j-w], c + dp[i][j]);
            }
        }
    }
    ll minc = 1e12;
    for(int i = 0;i <= p;i++)
    {
        minc = min(minc, dp[n][i]);
    }
    cout << fixed << setprecision(8);
    cout << minc / (double)n << endl;
    return 0;
}