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 (Clang 3.8.0) (judge verdict: Accepted)

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

#define true 0
#define false 1

int kaibun(char str[], int s, int l) {
  for (int i = s; i < l/2; i++) {
   	if (str[i] != str[l-i-1])
        return false;
  }
  return true;
}

int main() {
  char str[100];
  int len;
  
  scanf("%s\n", str);
  len = strlen(str);
  
  if ( kaibun(str, 0, len) == true ) {
    if ( kaibun(str, 0, (len-1)/2) == true ) {
      if ( kaibun(str, (len+3)/2, len-(len+3)/2) == true ) {
        printf("Yes\n");
        return 0;
      }
    }
  }
  printf("No\n");
  return 0;
}