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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
  $str = str_split(fgets(STDIN));
  $str_forward = array_slice($str, 0, (count($str)-1)/2);
  $str_backward = array_slice($str, (count($str)-1)/2+1);
  
  // print_r($str_forward);
  // print_r($str_backward);
  
  // if(is_palindrome($str) && is_palindrome($str_forward) && is_palindrome($str_backward))
  if(is_palindrome($str_forward) && implode('', $str_forward) == implode('', $str_backward))
    echo "Yes";
  else
    echo "No";
  
  function is_palindrome($str){
    $i = 0;
    $j = count($str)-1;
    for($i; $i<$j; $i++){
      if($str[$i] != $str[$j])
        return false;
      $j--;
    }
    return true;
  }
?>