import sys
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))

def main():
    inf=10**16
    n,p=MI()
    dp=[inf]*(p+1)
    dp[0]=0
    for _ in range(n):
        rank=LI()
        for i in range(p,-1,-1):
            dp[i]+=rank[0]
            if i-1>=0 and dp[i-1]+rank[1]<dp[i]:dp[i]=dp[i-1]+rank[1]
            if i-2>=0 and dp[i-2]+rank[2]<dp[i]:dp[i]=dp[i-2]+rank[2]
            if i-3>=0 and dp[i-3]+1<dp[i]:dp[i]=dp[i-3]+1

    print(dp[p]/n)

main()