N = 2
M = 1
K = 3

count = [0] * (N+1)
prev = [0] * (N+1)

count[0] = 1 # empty set

for i in range(K):
	# move count to prev
	for index in range(N+1):
		prev[index] = count[index]
		count[index] = 0
	
	# calculate new counts
	for prevSum in range(N+1):
		for value in range(M+1):
			newSum = min(N, prevSum+value)
			count[newSum] += prev[prevSum]
			
ans = (count[N] / pow(M+1, K))
print(ans)