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);
        String str = sc.next();
        boolean ans = isPalind(str, 0, str.length()) &&
                isPalind(str, 0, (str.length() - 1) / 2) &&
                isPalind(str, (str.length() + 3) / 2 - 1, str.length());
        System.out.println(ans ? "Yes" : "No");
    }

    static boolean isPalind(String str, int s, int e) {
        StringBuilder rsb = new StringBuilder();
        char[] C = str.toCharArray();
        for(int i = s; i < e - s; i++) {
            if(C[i] != C[e - i - 1]) return false;
        }
        return true;
    }
}