N, K = gets.split.map(&:to_i)
arr = Array.new
1.upto(N) do |i|
	arr.push(i)
end
ans = 0
arr.permutation(N) do |i|
	rev = 0
	0.upto(N - 2) do |j|
		rev += 1 if i[j] > i[j + 1]
	end
	ans += 1 if rev == 1 && i[0] == K
end
p ans