import numpy as np
import sys
def MI(): return map(int, sys.stdin.readline().split())

def main():
    inf=10**9
    n,p=MI()
    dp=[inf]*(p+1)
    dp[0]=0
    dp=np.array(dp,dtype="i8")
    for _ in range(n):
        a,b,c=MI()
        ndp=dp+a
        np.minimum(ndp[1:],dp[:-1]+b,out=ndp[1:])
        np.minimum(ndp[2:],dp[:-2]+c,out=ndp[2:])
        np.minimum(ndp[3:],dp[:-3]+1,out=ndp[3:])
        dp=ndp

    print(dp[p]/n)

main()