#include <bits/stdc++.h>
using namespace std;

#define pb         push_back

typedef long long ll;
const ll INF = 1000000000000000000ll;
const ll MOD = 1000000007ll;
const double EPS = 1e-8;

ll dp[5001][15001];

int main(void) {
	//ios_base::sync_with_stdio(false);
	//cin.tie(0);
	
	int n, p;
	cin >> n >> p;
	vector<int> a, b, c;

	a.pb(0);
	b.pb(0);
	c.pb(0);
	for(int i=0; i<n; i++){
		int ta, tb, tc;
		cin >> ta >> tb >> tc;

		a.pb(ta);
		b.pb(tb);
		c.pb(tc);
	}

	for(int i=1; i<=n; i++){
		for(int j=p; j>=0; j--){
			dp[i][j] = dp[i-1][j] + a[i];
			if(j-1 >= 0){
				dp[i][j] = min(dp[i][j], dp[i-1][j-1] + b[i]);
			}
			if(j-2 >= 0){
				dp[i][j] = min(dp[i][j], dp[i-1][j-2] + c[i]);
			}
			if(j-3 >= 0){
				dp[i][j] = min(dp[i][j], dp[i-1][j-3] + 1);
			}
		}
	}

	printf("%.8f\n", 1.0 * dp[n][p] / n);

	
	return 0;
}