#include<bits/stdc++.h>
#define int long long
const int inf=8938103643641919514ll;
const int mod=1000000007ll;
const int dd[]={0,-1,0,1,0};
using namespace std;
int a,b,c,d;
int p[5000],q[5000],r[5000],s[2][15001];
signed main(){
	int i,j,k;
	int f=0;
	cin>>a>>b;
	for(i=0;i<a;i++)
		cin>>p[i]>>q[i]>>r[i];
	for(i=0;i<a;i++){
		for(j=0;j<=b;j++)
			s[f^1][j]=s[f][j]+p[i];
		for(j=1;j<=b;j++)
			if(s[f^1][j]>=s[f][j-1]+q[i])
				s[f^1][j]=s[f][j-1]+q[i];
		for(j=2;j<=b;j++)
			if(s[f^1][j]>=s[f][j-2]+r[i])
				s[f^1][j]=s[f][j-2]+r[i];
		for(j=3;j<=b;j++)
			if(s[f^1][j]>=s[f][j-3]+1)
				s[f^1][j]=s[f][j-3]+1;
		f^=1;
	}
	cout<<setprecision(15)<<(double)s[f][b]/a<<endl;
}