#include "bits/stdc++.h"
using namespace std;
#define int unsigned int
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

int N,P;

void solve() {
    cin>>N>>P;
    int C[N][4];
    int DP[2][P+10];
    REP(i,N) cin>>C[i][0]>>C[i][1]>>C[i][2];
    REP(i,N) C[i][3]=1;

    REP(n,2)REP(p,P+10)DP[n][p]=INT_MAX;
    REP(i,min((int)4, P+1)) {
        DP[0][P-i]=C[0][i];
    }
    FOR(n,1,N) {
        REP(p,P+1) REP(i,4) {
            DP[n%2][p] = min(DP[n%2][p], DP[(n-1)%2][p+i] + C[n][i]);
        }
        REP(p,P+1) {
            DP[(n-1)%2][p] = INT_MAX;
        }
    }
    int mi = INT_MAX;
    REP(p,P+1) {
        mi = min((int)mi, DP[(N-1)%2][p]);
    }
    
    out("%.10lf\n", (double)mi/N);
}