#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <numeric>
#include <cstring>
#include <cmath>
#include <set>
#include <queue>
#include <stack>

const int MOD = 1e9 + 7;
const int iINF = 1000000000;
const long long int llINF = 1000000000000000000;
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;
using ll = long long int;
using P = pair<int, int>;
using edge = struct
{
    int to;
    int cost;
};

int dp[2][15010];
int s[5010][4];

int main()
{
    int N, P;
    cin >> N >> P;

    rep(i, N)
    {
        cin >> s[i][0] >> s[i][1] >> s[i][2];
        s[i][3] = 1;
    }

    rep(i, 2) rep(j, 15010) dp[i][j] = iINF;

    dp[0][0] = 0;

    rep(i, N)
    {
        rep(j, (P + 1))
        {
            rep(k, 4)
            {
                if (k + j <= P)
                    dp[1][j + k] = min(dp[0][j] + s[i][k], dp[1][j + k]);
            }
        }

        rep(j, P + 1)
        {
            dp[0][j] = dp[1][j];
            dp[1][j] = iINF;
        }
    }

    printf("%0.9f\n", (double)dp[0][P] / (double)N);
}