A string $S$ consisting of lowercase English letters is a good string if and only if it satisfies the following property for all integers $i$ not less than $1$:

-   There are exactly zero or exactly two different letters that appear exactly $i$ times in $S$.

Given a string $S$, determine if it is a good string.

The input is given from Standard Input in the following format:

```
$S$
```

Print `Yes` if $S$ is a good string, and `No` otherwise.

-   $S$ is a string of lowercase English letters with a length between $1$ and $100$, inclusive.

Yes

For the string commencement, the number of different letters that appear exactly i times is as follows:

• i=1: two letters (o and t)
• i=2: two letters (c and n)
• i=3: two letters (e and m)
• i≥4: zero letters

Therefore, commencement satisfies the condition of a good string.

No

For the string banana, there is only one letter that appears exactly one time, which is b, so it does not satisfy the condition of a good string.