import numpy as np

N, P = map(int, input().split())
dp = np.zeros(P + 1, dtype=int)

for _ in range(N):
    a, b, c = map(int, input().split())
    new_dp = dp + a
    new_dp[1:] = np.minimum(new_dp[1:], dp[:-1] + b)
    new_dp[2:] = np.minimum(new_dp[2:], dp[:-2] + c)
    new_dp[3:] = np.minimum(new_dp[3:], dp[:-3] + 1)
    dp = new_dp

print(dp[P] / N)