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 $S$.

Input is given from Standard Input in the following format:

```
$S$
```

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

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

Yes

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