using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, m) = (c[0], c[1]);
        var map = NArr(n);
        var bitmax = 1 << n;
        var dp = new double[bitmax][];
        for (var i = 0; i < dp.Length; ++i) dp[i] = Enumerable.Repeat(double.MinValue, m + 1).ToArray();
        dp[0][0] = 0;
        var visited = new bool[bitmax][];
        for (var i = 0; i < visited.Length; ++i) visited[i] = new bool[m + 1];
        DFS(n, bitmax, 0, 0, map, dp, visited);
        WriteLine(dp[0][0]);
    }
    static void DFS(int n, int bitmax, int b, int mi, int[][] map, double[][] dp, bool[][] visited)
    {
        if (visited[b][mi]) return;
        var max = 0.0;
        for (var i = 0; i < n; ++i)
        {
            if ((b & (1 << i)) != 0) continue;
            var nb = b | (1 << i);
            DFS(n, bitmax, nb, mi, map, dp, visited);
            max = Math.Max(max, dp[nb][mi] + 1.0 / map[i][0]);
            if (mi + 1 < dp[i].Length)
            {
                DFS(n, bitmax, b, mi + 1, map, dp, visited);
                max = Math.Max(max,
                    (1.0 / map[i][2]) * (dp[nb][mi] + 1.0 / map[i][1]) + (1.0 - 1.0 / map[i][2]) * dp[b][mi + 1]);
            }
        }
        visited[b][mi] = true;
        dp[b][mi] = max;
    }
    static void DebugTable<T>(T[][] table)
    {
        Console.WriteLine("{");
        foreach (var list in table) Console.WriteLine(string.Join(", ", list));
        Console.WriteLine("}");
    }
}