101320: [AtCoder]ABC132 A - Fifty-Fifty

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.

Sample Input 1

ASSA

Sample Output 1

Yes

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

Sample Input 2

STOP

Sample Output 2

No

Sample Input 3

FFEE

Sample Output 3

Yes

Sample Input 4

FREE

Sample Output 4

No