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 Scala (2.11.7) (judge verdict: Accepted)

import java.util._

object Main {
  def main(args: Array[String]): Unit = {
    val scanner = new Scanner(System.in)
    val string = scanner.nextLine
    val revString = string.reverse
    if (string != revString) {
      println("No")
      return
    }

    val firstHalf = string.substring((string.length - 1) / 2 + 1)
    if (firstHalf != firstHalf.reverse) {
      println("No")
      return
    }

    val secondHalf = string.substring((string.length - 1) / 2 + 1, string.length)
    if (secondHalf != secondHalf.reverse) {
      println("No")
      return
    }

    println("Yes")
  }
}