def is_valid_URL(str):
	import re
	
	regex = ("((http|https)://)(www.)?" +
			"[a-zA-Z0-9@:%._\\+~#?&//=]" +
			"{2,256}\\.[a-z]" +
			"{2,6}\\b([-a-zA-Z0-9@:%" +
			"._\\+~#?&//=]*)")
	p = re.compile(regex)
	if (str == None):
		return False
	if(re.search(p, str)):
		return True
	else:
		return False
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] 