#include<cstdio>
#include<algorithm>
using namespace std;

const int INF = 1000000000;

int main(){
	int n,p;
	int rnk[5000][4];
	int dp[15001];
	scanf("%d %d",&n,&p);
	for(int i=0;i<n;i++){
		scanf("%d %d %d",&rnk[i][0],&rnk[i][1],&rnk[i][2]);
		rnk[i][3] = 1;
	}
	fill(dp,dp+p,INF);
	dp[p] = 0;
	for(int i=0;i<n;i++){
		for(int j=0;j<=p;j++){
			dp[j] += rnk[i][0];
			for(int k=1;k<=3&&j+k<=p;k++){
				dp[j] = min(dp[j],dp[j+k]+rnk[i][k]);
			}
		}
	}
	printf("%.1f\n",(double)dp[0]/n);
	return 0;
}