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

fscanf(STDIN, "%s", $in_s);
$n = strlen($in_s);
$s1 = substr($in_s , 0, ($n / 2));
$s2 = substr($in_s , -($n / 2), ($n / 2));
//var_dump($in_s);
//var_dump($n);
//var_dump($s1);
//var_dump($s2);

$ans = "Yes";
for ($i = 0; $i < $n / 2; $i++) {
    if($in_s[$i] != $in_s[$n - $i - 1]){
    $ans = "No";
    }
}

$n1 = strlen($s1);
for ($i = 0; $i < $n1 / 2; $i++) {
    if($s1[$i] != $s1[$n1 - $i - 1]){
        $ans = "No";
    }
}

$n2 = strlen($s2);
for ($i = 0; $i < $n2 / 2; $i++) {
    if($s2[$i] != $s2[$n1 - $i - 1]){
        $ans = "No";
    }
}


echo "$ans\n";