import sys
if sys.platform =='ios':
	import clipboard
	a=clipboard.get()
	a = a.split('\n')
	text = '\n'.join(a)
	with open('input_file.txt','w') as f:
		f.write(text)
	sys.stdin = open('input_file.txt')
sys.setrecursionlimit(410000000)
stdin = sys.stdin 
ni = lambda: int(ns())
ni_1 = lambda: int(ns())-1
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().strip()
nm = lambda: map(int,input().split())
na_1 = lambda: list(map(lambda x:int(x)*(-1), stdin.readline().split()))
na_2 = lambda: list(map(lambda x:int(x)-1, stdin.readline().split()))

N,P = nm()
INF = 10**10
dp = [INF]*(P+1)
dp[0] = 0
for _ in range(N):
	a,b,c = nm()
	for i in range(P,-1,-1):
		mi = dp[i]+a
		if i >= 1:
			mi = min(mi,dp[i-1]+b)
		if i >= 2:
			mi = min(mi,dp[i-2]+c)
		if i >= 3:
			mi = min(mi,dp[i-3]+1)
			
		dp[i] = mi
		
print(dp[-1]/N)