using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;
using System.IO;

class Program
{
    static void Main()
    {
        new Magatro().Solve();
    }
}

class Magatro
{
    private int N, P;
    private int[] A, B, C;

    private void Scan()
    {
        var line = Console.ReadLine().Split(' ');
        N = int.Parse(line[0]);
        P = int.Parse(line[1]);
        A = new int[N];
        B = new int[N];
        C = new int[N];
        for (int i = 0; i < N; i++)
        {
            line = Console.ReadLine().Split(' ');
            A[i] = int.Parse(line[0]);
            B[i] = int.Parse(line[1]);
            C[i] = int.Parse(line[2]);
        }
    }

    public void Solve()
    {
        Scan();
        var dp = (new int[3 * P + 1]).Select(i => int.MaxValue).ToArray();
        dp[0] = 0;
        for (int i = 0; i < N; i++)
        {
            var next = (new int[3 * P + 1]).Select(ii => int.MaxValue).ToArray();
            for (int j = 3 * P; j >= 0; j--)
            {
                if (dp[j] != int.MaxValue)
                {
                    next[j + 0] = Math.Min(next[j + 0], dp[j] + A[i]);
                    next[j + 1] = Math.Min(next[j + 1], dp[j] + B[i]);
                    next[j + 2] = Math.Min(next[j + 2], dp[j] + C[i]);
                    next[j + 3] = Math.Min(next[j + 3], dp[j] + 1);
                }
            }
            dp = next;
        }
        Console.WriteLine((double)dp[P] / N);
    }
}