I'm having issues figuring out how to get my code to increment the string that is given by user input so that when a user chooses to replace a letter like z it would go to a, b to c ect. The catch is I have to do this without using boolean. I am supposed to get this by using arithmetics to get the promotion from z to a from the users input. Plus must be only lower case letters from a-z. Any help would be appreciated thanks.