Make a program that filters a list of strings and returns a list with only your friends name in it.
If a name has exactly 4 letters in it, you can be sure that it has to be a friend of yours! Otherwise, you can be sure he's not...
Input = ["Ryan", "Kieran", "Jason", "Yous"]
Output = ["Ryan", "Yous"]
Input = ["Peter", "Stephen", "Joe"]
Output = []
Input strings will only contain letters. Note: keep the original order of the names in the output.