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: Accepted)

<?php
//error_reporting(0);
$S = trim(fgets(STDIN));
//list($N,$M) = explode(" ",trim(fgets(STDIN)));
//$a = array_map('intval',explode(" ",trim(fgets(STDIN))));

$N=strlen($S);
$rev = strrev($S);
$p1 = substr($S,0,intdiv(($N-1),2));
$p1rev = strrev($p1);
$p2 = substr($S,-intdiv(($N-3),2)-1);
$p2rev = strrev($p2);

if (($S==$rev) && ($p1 == $p1rev) &&  ($p2 == $p2rev)) {
 printf("Yes\n");
}
else {
 printf("No\n");
}