说明：  正在启动ENG421 UoP学生的模板，以开始编程简单的密码程序，该程序接收来自用户的消息...
(Starting template for ENG421 Students at the UoP to begin programming a simple Cryptogram program, which takes in a message from the user and encrypts/decrypts a message based on a key value shifting letters by a numeric value.)