Create the username portion of a registration system that requires all usernames are unique. If a new user requests a name that is already used, an integer should be added to the end of the username to make it unique The numbering begins with 1 and is incremented by 1 for each new instance per user name.
Example1:
Input
alex
xylos
alex
alan
Output
alex
xylos
alex1
alan
Example2:
Input
John
Peter
Sam
John
Sam
Rock
John
Output
John
Peter
Sam
John1
Sam1
Rock
John2