#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int r[5010][4];

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N, P;
    cin >> N >> P;
    rep(i, N)rep(j, 3)cin >> r[i][j];
    rep(i, N)r[i][3] = 1;
    
    ll INF = LLONG_MAX / 4;
    vll cu(P + 1, INF), ne(P + 1, INF);
    cu[0] = 0;

    rep(i, N) {
        fill(all(ne), INF);
        ll x;
        for(int j = 0; j <= P; ++j)if((x = cu[j])<INF) {
            for(int p = 0; p <= 3; ++p) if(j+p<=P){
                smin(ne[j + p], x+r[i][p]);
            }
        }
        swap(cu, ne);
    }

    cout << setprecision(20) << cu[P] / (double)N << endl;
}