Problem:
Score : 100 points

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

Solution in PyPy3 (2.4.0) (judge verdict: Accepted)

S = input()

alfa = [chr(i) for i in range(97,97+26)]

A = []


counter = []
for i in range(4):
    counter.append(S.count(S[i]))

flag = 0
for i in range(4):
    if counter[i] == 2:
        flag += 1

if flag > 3:
    print('Yes')
else:
    print('No')