#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <utility>
#include <sstream>
#include <complex>
#include <fstream>
#include <bitset>
#include <time.h>
#include <tuple>
#include <iomanip>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef vector<ll> V;
typedef complex<double> Point;

#define PI acos(-1.0)
#define EPS 1e-10
const ll INF = 1e16;
const ll MOD = 1e9 + 7;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define rep(i,N) for(int i=0;i<(N);i++)
#define ALL(s) (s).begin(),(s).end()
#define EQ(a,b) (abs((a)-(b))<EPS)
#define EQV(a,b) ( EQ((a).real(), (b).real()) && EQ((a).imag(), (b).imag()) )
#define fi first
#define se second
#define N_SIZE (1LL << 20)
#define NIL -1

ll sq(ll num) { return num*num; }
ll mod_pow(ll x, ll n) {
	if (n == 0)return 1;
	if (n == 1)return x%MOD;
	ll res = sq(mod_pow(x, n / 2));
	res %= MOD;
	if (n % 2 == 1) {
		res *= x;
		res %= MOD;
	}
	return res;
}
ll mod_add(ll a, ll b) { return (a + b) % MOD; }
ll mod_sub(ll a, ll b) { return (a - b + MOD) % MOD; }
ll mod_mul(ll a, ll b) { return a*b % MOD; }

ll n,p;
ll C[5001][4];
ll dp[2][3*5000+1];

int main(){
	cin >> n >> p;
	rep(i,n){
		cin >> C[i][0] >> C[i][1] >> C[i][2];
		C[i][3] = 1;
	}
	rep(i,2)rep(j,3*5000+1)dp[i][j] = INF;
	rep(i,4)dp[1][i] = C[0][i];
	FOR(i,1,n){
		rep(j,p+1){
			rep(k,4){
				if(j+k <= p)dp[(i+1)%2][j+k] = min(dp[(i+1)%2][j+k],dp[i%2][j]+C[i][k]);
			}
		}
		rep(j,p+1)dp[i%2][j] = INF;
	}
	// rep(i,p+1){
		// cout << i << " ";
		// printf("%.10lf\n",(double)dp[n%2][i]/(double)n);
	// }
	printf("%.10lf\n",(double)dp[n%2][p]/(double)n);
}