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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner entrada= new Scanner(System.in);
        String str=entrada.next();
        String str2="";
        int p=-2;
        int cont=0;
        for(int i=0; i<str.length();i++){
            char c=str.charAt(i);
            for(int j=0;j<str.length();j++){
                if(str.charAt(j)==(c)){
                    cont+=1;
                }
            }
        }
        if (cont==8){
            System.out.println("Yes");
        }
        else{
            System.out.println("No");
        }
        //System.out.println(cont);
    }
}