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 C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
int main(void)
{
	char s[5]="";
	int i=0;
	scanf("%s",s);
	
	
	
	 if(s[0]==s[1]&&s[2]==s[3]){
		if(s[0]==s[2]&&s[0]==s[3])
		puts("No");
		else
		puts("Yes");
	}
	
	else if(s[0]==s[2]&&s[1]==s[3]){
		if(s[0]==s[1]&&s[0]==s[3])
		puts("No");
		else
		puts("Yes");
	}

	
	else
	puts("No");

	return 0;
}