#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N,P;
int A[5];
ll from[15050];
ll to[15050];

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>P;
	FOR(i,3*N+1) from[i]=1<<30;
	from[P]=0;
	
	FOR(i,N) {
		FOR(j,3*N+1) to[j]=1<<30;
		cin>>A[0]>>A[1]>>A[2];
		A[3]=1;
		FOR(j,P+1) FOR(x,4) if(j>=x) to[j-x]=min(to[j-x],from[j]+A[x]);
		swap(from,to);
	}
	_P("%.12lf\n",from[0]*1.0/N);
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n';
	FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	solve(); return 0;
}