N = int(input())
K = int(input())
jiro = [0 for j in range(70 + 1)]
taro = [0 for j in range(70 + 1)]
jiro[0] = 1.0
taro[0] = 1.0
for i in range(N):
	for j in range(60,-1,-1):
		for k in range(1,6 + 1):
			jiro[j + k] += jiro[j] / 6
		jiro[j] = 0.0
for i in range(K):
	for j in range(60,-1,-1):
		for k in range(4,6 + 1):
			taro[j + k] += taro[j] / 3
		taro[j] = 0.0
for i in range(K,N):
	for j in range(60,-1,-1):
		for k in range(1,6 + 1):
			taro[j + k] += taro[j] / 6
		taro[j] = 0.0
ans = 0.0
for i in range(60 + 1):
	for j in range(i + 1,60 + 1):
		ans += jiro[i] * taro[j]
print (ans)