#include<bits/stdc++.h>
using namespace std;
#define inf INT_MAX
#define INF LLONG_MAX
#define ll long long
#define ull unsigned long long
#define M (int)(1e9+7)
#define P pair<int,int>
#define PLL pair<ll,ll>
#define FOR(i,m,n) for(int i=(int)m;i<(int)n;i++)
#define RFOR(i,m,n) for(int i=(int)m;i>=(int)n;i--)
#define rep(i,n) FOR(i,0,n)
#define rrep(i,n) RFOR(i,n,0)
#define all(a) a.begin(),a.end()
#define IN(a,n) rep(i,n){ cin>>a[i]; }
const int vx[4] = {0,1,0,-1};
const int vy[4] = {1,0,-1,0};
#define PI 3.14159265
#define F first
#define S second
#define PB push_back
#define EB emplace_back
#define int ll
#define vi vector<int>

int dp[5010][15010];

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

  int n,p;
  cin>>n>>p;
  vector<vi> v(n,vi(3));

  rep(i,n){
    rep(j,3){
      cin>>v[i][j];
    }
  }

  rep(i,n+1){
    rep(j,p+1){
      dp[i][j]=INF;
    }
  }

  dp[0][0]=0;

  rep(i,n){
    rep(j,i*3+1){
      rep(k,4){
        if(j+k>p) break;
        int t;
        if(k==3) t=1;
        else t=v[i][k];
        dp[i+1][j+k]=min(dp[i+1][j+k],dp[i][j]+t);
      }
    }
  }

  printf("%.10lf\n",(double)dp[n][p]/(double)n);
  

}