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.Scanner;

public class Main {

	public static void main(String args[])
	{
		Scanner scan=new Scanner(System.in);
		String s=scan.next().toUpperCase();
		char a[]=s.toCharArray();
		int count=0;
		int freq[]=new int[26];
		for(int i=0;i<a.length;i++)
		{
			freq[a[i]-'A']++;
		}
		for(int i=0;i<26;i++)
		{
			if(freq[i]==2 ||freq[i]==0) {
				
			}else {
				System.out.println("No");
				return;
			}
		}
		System.out.println("Yes");
	}
	
}