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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <iostream>

using namespace std;

int main()
{
    string S;
    getline (cin , S);
    if (S[0] == S[1]) {
            if (S[2]==S[3]){
            cout<< "Yes";
            }
            else {
                cout<< "No";
            }
    }
    else if (S[0] == S[2]) {
        if (S[1] == S[3]){
            cout<< "Yes";
        }
        else {
            cout<< "No";
        }
    }
    else if (S[0] == S[3]) {
        if (S[1] == S[2]){
            cout<< "Yes";
        }
        else {
            cout<< "No";
        }
    }
    else {
        cout<< "No";
    }



    return 0;
}