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-----
ASSA

-----Sample Output-----
Yes

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

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