#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<typename T> using Graph = vector<vector<T>>;

#define REP(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, a) REP(i, 0, a)
#define EACH(i, a) for (auto i: a)
#define ITR(x, a) for (__typeof(a.begin()) x = a.begin(); x != a.end(); x++)
#define ALL(a) (a.begin()), (a.end())
#define HAS(a, x) (a.find(x) != a.end())
#define endl '\n'

const int inf = 1e9;
int N, P;
int dp[15005][5005];

int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin >> N >> P;
  rep(i, P + 1) dp[i][0] = inf;
  rep(i, N) {
    int a, b, c;
    cin >> a >> b >> c;
    if (i == 0) {
      dp[0][0] = a; dp[1][0]  = b; dp[2][0]  = c; dp[3][0]  = 1;
    }
    else {
      for (int j = P; j > -1; j--) {
        dp[j][0]  = dp[j][0]  + a;
        if (j > 0) dp[j][0]  = min(dp[j][0] , dp[j - 1][0]  + b);
        if (j > 1) dp[j][0]  = min(dp[j][0] , dp[j - 2][0]  + c);
        if (j > 2) dp[j][0]  = min(dp[j][0] , dp[j - 3][0]  + 1);
      }
    }
  }

  printf("%.10f", 1.0*dp[P][0] /N);

  return 0;
}