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.