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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;

int main()
{
       char S[4];
      cin>> S;

       if(S[0]==S[1] && S[2]==S[3])
       {
              cout<< "Yes"<< endl;
       }
       else if (S[0]==S[2] && S[1]==S[4])
              {
              cout<< "Yes"<< endl;
       }
       else if (S[0]==S[3] && S[1]==S[2])
              {
              cout<< "Yes"<< endl;
       }
       else
       {
              cout<<"No"<< endl;
       }
}