Problem:
Score : 200 points

Problem Statement

A string S of an odd length is said to be a strong palindrome if and only if all of the following conditions are satisfied:

S is a palindrome.

Let N be the length of S. The string formed by the 1-st through ((N-1)/2)-th characters of S is a palindrome.

The string consisting of the (N+3)/2-st through N-th characters of S is a palindrome.

Determine whether S is a strong palindrome.

Constraints

S consists of lowercase English letters.

The length of S is an odd number between 3 and 99 (inclusive).

Input

Input is given from Standard Input in the following format:

S

Output

If S is a strong palindrome, print Yes;
otherwise, print No.

Sample Input 1

akasaka

Sample Output 1

Yes

S is akasaka.

The string formed by the 1-st through the 3-rd characters is aka.

The string formed by the 5-th through the 7-th characters is aka.
All of these are palindromes, so S is a strong palindrome.

Sample Input 2

level

Sample Output 2

No

Sample Input 3

atcoder

Sample Output 3

No

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>

int main(){
  int i,n,flag=0;
  char a[100];
  gets(a);
  n=strlen(a);
  for(i=0;i<n/2;i++){
    if(a[i]==a[n-i]){
      flag++;
    }
  }
  for(i=0;i<n/4;i++){
    if(a[i]==a[(n-1)/2-i]){
      flag++;
    }
  }
  for(i=0;i<n/4;i++){
    if(a[(n+3)/2+i]==a[n-i]){
      flag++;
    }
  }
  if(flag==0){
    printf("NO");
  }else{
    printf("YES");
  }
  return 0;
}