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クラスのインスタンスの生成
        Scanner sc = new Scanner(System.in);
        
        String[] ss = sc.next().split("");
      
        if(ss[0].equals(ss[1]) && ss[2].equals(ss[3])) {
        	System.out.println("Yes");
        } else if (ss[0].equals(ss[2]) && ss[1].equals(ss[3])) {
        	System.out.println("Yes");
 
        } else if (ss[0].equals(ss[3]) && ss[1].equals(ss[2])) {
        	System.out.println("Yes");
        } else {
        	System.out.println("No");
        }
	}
 
}