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: Accepted)

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		String S = sc.next();
		int N = S.length();
		
		String firstHalf = S.substring(0, (N-1)/2);
		String secondHalf = S.substring((N+3)/2 - 1);
		
		// 結果の出力
		if (isPalindrome(S) && isPalindrome(firstHalf) && isPalindrome(secondHalf)) {
			System.out.println("Yes");
		}
		else {
			System.out.println("No");
		}		

		sc.close();
	}
	
	static boolean isPalindrome (String s) {
		int n = s.length();
		for (int i=0; i<n/2; i++) {
			if (s.charAt(i)!=s.charAt(n-i-1)) {return false;}
		}
		return true;
	}
}