You need a username and a password to login. A username consists only of lowercase letters and is composed of the first letter of your first name and the letters of your last name.

Assignment

Determine the username of a person. This is done in the following way:

Write a function first_letter that takes the name of a person (str). The function must return the first letter (str) of that name.
Write a function username that takes the first name (str) and the last name (str) of a person. The function must return the username (str) of that person.

Example

        >>> first_letter('Sansa')
'S'
>>> first_letter('Jon')
'J'

>>> username('Sansa', 'Stark')
'sstark'
>>> username('Jon', 'Snow')
'jsnow'