Write a program that requests the user to enter an alphabetic character. Then convert the character from upper case to lower case or lower case to upper case. Print an error message if the user enters something other than an alphabetic character.

For example:

Enter an alphabetic character: A

Your input A converted to lower case is a.

Enter an alphabetic character: t

Your input t converted to upper case is T.

Enter a single digit or an alphabetic character: 9

You entered 9, which is not a letter.