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) {
		// TODO 自動生成されたメソッド・スタブ
		Solve s= new Solve();
		s.solve();
	}

}
class Solve{
	 Scanner sc = new Scanner(System.in) ;

	 void solve() {
	 String S=sc.next();
	 char[] s=new char[4];
	 boolean judge1 =false;
	 boolean judge2 =false;

	 for(int i=0;i<4;i++) {
		s[i]=S.charAt(i);
	 }
	 char s1='a';

	 for(int i=0;i<3;i++) {
		if(s[i]==s[i+1]&&judge1==false) {
			judge1=true;
			s1=s[i];
		}else if(s[i]==s[i+1]&&judge1==true&&s[i]!=s1) {
			judge2=true;
			i=5;
		}
	
	 }



	 if(judge1==true&&judge2==true) {
		 System.out.println("Yes");
	 }else {
		 System.out.println("No");
	 }


	 }
}