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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    val s = readLine() ?: return
    fun isPalindrome(value: String): Boolean {
        var i = 0
        var j = value.length - 1
        while (i <= j) {
            if (value[i] != value[j]) {
                return false
            }
            i++
            j--
        }
        return true
    }

    val n = s.length
    val s1 = s.substring(0, (n - 1) / 2)
    val s2 = s.substring((n + 3) / 2 - 1, n)

    System.err.println(s1)
    System.err.println(s2)

    if (isPalindrome(s) && isPalindrome(s1) && isPalindrome(s2)) {
        println("Yes")
    } else {
        println("No")
    }
}