#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }

int main() {
	int N; int P;
	while (~scanf("%d%d", &N, &P)) {
		vector<vector<int> > As(N, vector<int>(3));
		for (int i = 0; i < N; ++i) for (int j = 0; j < 3; ++j)
			scanf("%d", &As[i][j]);
		vector<int> dp, ndp(P + 1, INF);
		ndp[0] = 0;
		rep(i, N) {
			dp.swap(ndp);
			ndp.assign(P + 1, INF);
			int as[4] = { As[i][0], As[i][1], As[i][2], 1 };
			rer(j, 0, P) {
				int x = dp[j];
				if (x == INF) continue;
				rer(k, 0, 3) if(j + k <= P)
					amin(ndp[j + k], x + as[k]);
			}
		}
		int sum = *min_element(ndp.begin(), ndp.end());
		double ans = sum * 1. / N;
		printf("%.10f\n", ans);
	}
	return 0;
}