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: Wrong Answer)

import java.util.Scanner;
public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   String S = sc.next();
   if(S.charAt(0)==S.charAt(1)){
     if(S.charAt(2)==S.charAt(3)){
     System.out.println("Yes");
     }
   }else if(S.charAt(0)==S.charAt(2)){
     if(S.charAt(1)==S.charAt(3)){
     System.out.println("Yes");
     }
   }else if(S.charAt(0)==S.charAt(3)){
     if(S.charAt(1)==S.charAt(2)){
     System.out.println("Yes");
     }
   }else if(S.charAt(1)==S.charAt(2)){
     if(S.charAt(0)==S.charAt(3)){
     System.out.println("Yes");
     }
   }else if(S.charAt(1)==S.charAt(3)){
     if(S.charAt(0)==S.charAt(2)){
     System.out.println("Yes");
     }
   }else if(S.charAt(2)==S.charAt(3)){
     if(S.charAt(0)==S.charAt(1)){
     System.out.println("Yes");
     }
   }else{
     System.out.println("No");
   }
  
 }
}