Fifty-Fifty

题目描述

You are given a $4$-character string $S$ consisting of uppercase English letters. Determine if $S$ consists of exactly two kinds of characters which both appear twice in $S$.

输入格式

Input is given from Standard Input in the following format: $S$

输出格式

If $S$ consists of exactly two kinds of characters which both appear twice in $S$, print $Yes$; otherwise, print $No$.

ASSA

Yes

STOP

No

FFEE

Yes

FREE

No

提示

The length of $S$ is $4$. $S$ consists of uppercase English letters.$S$ consists of $A$ and $S$ which both appear twice in $S$.

标签: AtCoder|abc132A

来源

AtCoder|abc132A