"""

>>> validate([4, 5, 5, 6, 7, 3, 7, 5, 8, 6, 8, 9, 9, 8, 5, 5])
Valid!

>>> validate([6, 5, 1, 6, 4, 3, 7, 5, 1, 6, 4, 9, 3, 8, 5, 4])
Invalid!

"""

def validate(account_number):
   #Write your code here.
   return
