# Python 语言程序设计（2017 年秋）

1015. Case Transformation

Input a line of charactors, replace all lowercase letters with corresponding uppercase letters and all uppercase letters with corresponding lowercase letters, and output the string.

### 输入格式

Only one line, representing the string that needs to be transform.

### 输出格式

Only one line, the result string.

### 样例

Input
Hello, world!

Output
hELLO, WORLD!


### 提示

All non-letter characters should not be transformed.