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Score : $100$ points

### Problem Statement

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 $S$.

### Constraints

• The length of $S$ is $4$.
• $S$ consists of uppercase English letters.

### Input

Input is given from Standard Input in the following format:

$S$

### Output

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

ASSA

### Sample Output 1

Yes

$S$ consists of A and S which both appear twice in $S$.

STOP

No

FFEE

Yes

FREE

No