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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;
public class Main {// Main
  
  static boolean isPalindrome(char str[], int l, int h) 
    { 
        while (h > l) 
        { 
            if (str[l++] != str[h--]) 
            { 
                return false; 
            } 
        } 
        return true; 
    } 
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        int n = s.length();
        if(n%2==0) {
            System.out.println("NO");
        }
        else {
            if( isPalindrome(s.toCharArray(), 0, (n-3)/2) && isPalindrome(s.toCharArray(), (n+1)/2, n-1) ) System.out.println("YES");
            else System.out.println("NO");
        }
    }
}