#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <cassert>
using namespace std;

#define GET_ARG(a,b,c,F,...) F
#define REP3(i,s,e) for (i = s; i <= e; i++)
#define REP2(i,n) REP3 (i,0,(int)(n)-1)
#define REP(...) GET_ARG (__VA_ARGS__,REP3,REP2) (__VA_ARGS__)
#define RREP3(i,s,e) for (i = s; i >= e; i--)
#define RREP2(i,n) RREP3 (i,(int)(n)-1,0)
#define RREP(...) GET_ARG (__VA_ARGS__,RREP3,RREP2) (__VA_ARGS__)
#define DEBUG(x) cerr << #x ": " << x << endl

const int INF = 1e9;

int dp[2][15000];

int main(void) {
    int i, j, k, n, p;
    cin >> n >> p;
    REP (i,n) {
        int a[4];
        REP (k,3) cin >> a[k];
        a[3] = 1;
        REP (j,0,p) dp[(i+1)%2][j] = INF;
        REP (j,0,p) {
            REP (k,4) if (j >= k) {
                dp[(i+1)%2][j-k] = min(dp[(i+1)%2][j-k],dp[i%2][j] + a[k]);
            }
        }
    }
    printf("%.7f\n",(double)dp[n%2][0]/n);
    return 0;
}