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

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 dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

//dp[i][j] := i番目までのコンテストで，j問解いた時の順位の合計の最小値

int dp[2][15010];
int input[4];

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

    input[3] = 1;

    rep(i, 2) rep(j, P + 1) dp[i][j] = iINF;

    dp[0][0] = 0;

    rep(i, N)
    {
        rep(j, 3) cin >> input[j];

        rep(j, P + 1)
        {
            rep(x, 4)
            {
                if(j - x < 0) continue;
                dp[1][j] = min(dp[1][j], dp[0][j - x] + input[x]);
            }
        }

        swap(dp[0], dp[1]);

        fill(dp[1], dp[1] + P, iINF);
    }

    printf("%.9f\n", (double)dp[0][P] / (double)N);
    return 0;
}