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: Accepted)



import java.util.Arrays;
import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		String str=sc.next();
		
		char[] arr=str.toCharArray();
		int[] nums=new int[4];
		for(int i=0;i<nums.length;i++) {
			nums[i]=(int)arr[i];
		}
		Arrays.sort(nums);
		if(nums[0]!=nums[3] && nums[0]==nums[1] && nums[2]==nums[3]) {
			System.out.println("Yes");
		}else {
			System.out.println("No");
		}
		
	}
}