import sys
readline=sys.stdin.readline

N,P=map(int,readline().split())
inf=1<<30
dp=[inf]*(P+1)
dp[0]=0
for _ in range(N):
    a,b,c=map(int,readline().split())
    for i in range(P,-1,-1):
        dp[i]+=a
        if 0<=i-1:
            dp[i]=min(dp[i],dp[i-1]+b)
        if 0<=i-2:
            dp[i]=min(dp[i],dp[i-2]+c)
        if 0<=i-3:
            dp[i]=min(dp[i],dp[i-3]+1)
ans=dp[P]/N
print(ans)