cAPS lOCK

输入一个单词，若它的所有字母都是大写或只有第一个字母是小写，将这个单词的所有字母大小写反转后输出，否则按照原来的输入将这个单词输出。 输入：只有一行，包含一个只有大小写字母的单词。 输出：只有一行，为处理过后的单词。 感谢@daifucong 提供的翻译

wHAT DO WE NEED cAPS LOCK FOR? Caps lock is a computer keyboard key. Pressing it sets an input mode in which typed letters are capital by default. If it is pressed by accident, it leads to accidents like the one we had in the first passage. Let's consider that a word has been typed with the Caps lock key accidentally switched on, if: - either it only contains uppercase letters; - or all letters except for the first one are uppercase. In this case we should automatically change the case of all letters. For example, the case of the letters that form words "hELLO", "HTTP", "z" should be changed. Write a program that applies the rule mentioned above. If the rule cannot be applied, the program should leave the word unchanged.

The first line of the input data contains a word consisting of uppercase and lowercase Latin letters. The word's length is from 1 to 100 characters, inclusive.

Print the result of the given word's processing.

cAPS

Caps

Lock

Lock