#include <iostream>
#include <string>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <map>
#include <cmath>
#include <queue>
#include <utility>
#include <functional>
#include <deque>
#include <cctype>
#include <stack>
#include <bitset>
#include <set>

using ll = long long;
using namespace std;
typedef unsigned long long ull;
typedef pair<ll, ll> P;

const ll MOD = 1000000007;
const ll INF = 1 << 30;
const ll INF2 = 9000000000000000000LL;
const double INF3 = 900000000000000;
const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
const int tx[8] = { -1,0,1,-1,1,-1,0,1 }, ty[8] = { -1,-1,-1,0,0,1,1,1 };
#define ALL(x) (x).begin(),(x).end()



int main() {
	ll n, p, dp[2][15010], t[5010][5];
	double ans = INF3;
	cin >> n >> p;
	for (int i = 0;i < n;i++) {
		cin >> t[i][0] >> t[i][1] >> t[i][2];
		t[i][3] = 1;
	}
	for (int i = 0;i < 2;i++)for (int j = 0;j <= 15000;j++)dp[i][j] = INF;
	dp[0][0] = 0;
	for (int i = 0;i < n;i++) {
		for (int j = 0;j <= p;j++) {
			for (int k = 0;k < 4;k++) {
				if (j + k <= p)dp[1][j + k] = min(dp[0][j] + t[i][k], dp[1][j + k]);
			}
		}
		for (int j = 0;j <= p;j++) {
			dp[0][j] = dp[1][j];
			dp[1][j] = INF;
		}
	}
	for (int i = 0;i <= p;i++) {
		ans = min(ans, (double)((double)dp[0][i] /(double) n));
	}
	cout <<setprecision(16)<< ans << endl;
}