def check_email(email):
	import re 
	regex = '^[a-z0-9]+[\._]?[a-z0-9]+[@]\w+[.]\w{2,3}$'
	 
	if(re.search(regex,email)): 
		return ("Valid Email") 
	else: 
		return ("Invalid Email") 
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] 