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.*;
class Main{
  public static void main(String [] args) {
			Scanner sc = new Scanner(System.in);
			String str = sc.nextLine();
			int len = str.length();
			String str1 = str.substring(0, (len-1)/2+1);
			String str2 = str.substring((len+3)/2);
			if(checkPal(str) && checkPal(str1) && checkPal(str2)) {
				System.out.println("Yes");
			}
			else {
				System.out.println("No");
			}
	}

	private static boolean checkPal(String str) {
		// TODO Auto-generated method stub
		int i = 0, j = str.length() - 1; 
		  
        while (i < j) { 
              if (str.charAt(i) != str.charAt(j)) 
                return false; 
 
            i++; 
            j--; 
        } 
		return true;
	}
}