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frontback

Instructions

Write a program that prints the previous letter and the next letter of the Latin alphabet.

• If the number of arguments is different from 1, print a new line \n.
• If the length of the argument is different from 1, print a new line \n.
• If the argument is not a letter, print a new line \n.
• There are no letters to print before a or after z.

Usage

$ go run . | cat -e
$
$ go run . a | cat -e
ab$
$ go run . "B" | cat -e
ABC$
$ go run . "z" | cat -e
yz$
$ go run . "Hello World!" | cat -e
$
$ go run . "1" | cat -e
$