AT_scpc2026_div3_a Find the Missing Letter
Description
#### 表示言語
/ / flakepym was typing the string `SCSC` on his computer and accidentally omitted one character. Find the missing character.
Input Format
The input is given from Standard Input in the following format:
> $ S $
Output Format
Output the omitted character as an uppercase letter.
Explanation/Hint
### Constraints
- The string $ S $ has length $ 3 $ and consists only of the uppercase letters `S` and `C`.
- The given string can be obtained by removing exactly one character from `SCSC`.