#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int N, P;
ll v[5010][4];
ll dp[5010][15010];

int main() {
  cin >> N >> P;
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < 3; j++) {
      cin >> v[i][j];
    }
    v[i][3] = 1;
  }

  fill(dp[0], dp[5010], 1LL << 60);
  for (int i = 0; i < 4; i++) {
    dp[1][i] = v[0][i];
  }
  for (int i = 1; i < N; i++) {
    for (int j = 0; j <= P; j++) {
      for (int k = 0; j - k >= 0; k++) {
        dp[i + 1][j] = min(dp[i + 1][j], dp[i][j - k] + v[i][k]);
      }
    }
  }
  printf("%f\n", (double)dp[N][P] / N);

  return 0;
}