#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
using namespace std;
typedef long long ll;
typedef pair<int, int> P;

int main(){
    int N, P;
    cin >> N >> P;
    ll rank[N][4];
    ll a, b, c;
    rep(i,0,N){
        cin >> a >> b >> c;
        rank[i][0] = a;
        rank[i][1] = b;
        rank[i][2] = c;
        rank[i][3] = 1;
    }
    
    vector<vector<ll> > dp(2, vector<ll>(P+1, 1e18));
    dp[0][0] = 0;

    rep(i,0,N) {
        rep(j,0,P+1) rep(k,0,4){
            if(j-k>=0){
                dp[1][j] = min(dp[0][j-k] + rank[i][k], dp[1][j]);
            }
        }
        rep(j,0,P+1){
            dp[0][j] = dp[1][j];
            dp[1][j] = 1e18;
        }
    }
    double ans = (double)dp[0][P]/(double)N;
    printf("%.5f\n", ans);
    return 0;   
}