#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, x> #define vector2(type) vector > #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); }