def max_height(node):
	class Node: 
		def __init__(self, data): 
			self.data = data 
			self.left = None
			self.right = None
	 
	if node is None: 
		return 0 ; 
	else : 
		left_height = max_height(node.left) 
		right_height = max_height(node.right) 
		if (left_height > right_height): 
			return left_height+1
		else: 
			return right_height+1
def count_ways(n):
	 
	A = [0] * (n + 1) 
	B = [0] * (n + 1) 
	A[0] = 1
	A[1] = 0
	B[0] = 0
	B[1] = 1
	for i in range(2, n+1): 
		A[i] = A[i - 2] + 2 * B[i - 1] 
		B[i] = A[i - 1] + B[i - 2] 
	return A[n] 