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;

class Main{
public static void main(String[] args){
  Scanner sc = new Scanner(System.in);
  String S = sc.next();
  String[] Ssplit = S.split("");
  int ans = 0;
  int ans1 = 0;
  int ans2 = 0;
  if(Ssplit[0].equals(Ssplit[1]))
  ans =+ 1;
  if(Ssplit[0].equals(Ssplit[2]))
  ans =+ 1;
  if(Ssplit[0].equals(Ssplit[3]))
  ans =+ 1;
  if(ans != 1)
  System.out.println("No");
  
  if(ans == 1){
  if(Ssplit[1].equals(Ssplit[0]))
  ans1 =+ 1;
  if(Ssplit[1].equals(Ssplit[2]))
  ans1 =+ 1;
  if(Ssplit[1].equals(Ssplit[3]))
  ans1 =+ 1;
  if(ans1 != 1)
  System.out.println("No");
  }
  
  if(ans1 == 1){
  if(Ssplit[2].equals(Ssplit[0]))
  ans2 =+ 1;
  if(Ssplit[2].equals(Ssplit[1]))
  ans2 =+ 1;
  if(Ssplit[2].equals(Ssplit[3]))
  ans2 =+ 1;
  if(ans2 != 1)
  System.out.println("No");
  }
  if(ans == 1 & ans1 == 1 & ans2 == 1)
  System.out.println("Yes");
}
}