说明：  据说最早的密码来自于罗马的凯撒大帝。消息加密的办法是：对消息原文中的每个字母，分别用该字母之后的第5个字替换（例如：消息原文中的每个字母A都分别替换成字母F）。而你要做的消息原文，也就是要这个过程反过来。 密码字母：A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 原文字母：V W X Y Z A B C D E F G H I J K L M N O P Q R S T U (注意：只是字母发生替换，其他非字母的字符不变，并且消息原文的所有字母都是大写。)
(It is said that the earliest code came from Caesar the great in Rome. The method of message encryption is to replace each letter in the original message with the fifth word after the letter (for example, each letter A in the original message is replaced with the letter F). The original message you need to do is to reverse the process. Password letter: a B C D E F G H I J L M n o p q r s t U V W x y z Original letter: V W x y z a B C D E F H I J L M n o p q r s t u (Note: only letters are replaced, other non alphabetic characters remain unchanged, and all letters in the original message are capitalized. ))