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();

        int miss = 0;

        for(int i = 0; i <= 3; i++){
            if(!(S.charAt(0) == S.charAt(i))){
                miss++;
            }

            if(i == 3) {
                if (miss >= 3) {
                    if(S.charAt(1) == S.charAt(2)){
                        System.out.println("Yes");
                        return;
                    }
                    System.out.println("No");
                    return;
                }else{
                    System.out.println("Yes");
                }
            }
        }


    }
}