N, P = map(int, input().split())
contests = [list(map(int, input().split())) for _ in range(N)]
dp = [float('inf')] * (P + 1)
dp[0] = 0
for i in range(N):
  a = contests[i]
  nxt = [float('inf')] * (P + 1)
  for j in range(P + 1):
    if dp[j] == float('inf'): continue
    for k in range(3, -1, -1):
      if k < 3:
        add = a[k]
      else:
        add = 1
      if j + k <= P:
        nxt[j + k] = min(nxt[j + k], dp[j] + add)
  dp = nxt
  #print(dp)
print(dp[P] / N)