破译密码：有个叫“猪头帮”的国家，采用一种简单的文法加密，他们所用的语言里面只有大写字母，没有其他任何字符；现在还知道他们加密的方法是：只用一个大写字母和原文进行异或运算生成密文。请你帮忙解开。-Code-breaking: a man named "pig gang" of countries, using a simple grammar encryption, they use language which only capital letters, no other characters　now know that their encryption method is: only one capital letter and the original XOR the ciphertext. Please help solve.