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++14 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <string.h>
using namespace std;
int main()
{
int count=0;
string s;
cin>>s;
for (int i=0;i<4;i++)
  for (int j=i+1;j<4;j++)
  {
if(s[i]==s[j])
 { count+=1;
  i++;
j++;
break;}
else
{if(i==j)
break;
else
continue;
    }
}
if(count==2)
cout<<"yes";
else
cout<<"no";
}