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;
class Main{
    public static void main(String[] args) {
        Scanner input=new Scanner(System.in);
        char []S;
        int count=0;
        S=input.next().toCharArray();
        for(int i=0;i<3;i++)
        {
            for(int j=i+1;j<4;j++)
            {
                if(S[i]==S[j])
                {
                    count++;
                }
            }
        }
        if(count==2)
        {
            System.out.println("Yes");
        }
        else
            System.out.println("N0");
    }
}