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 (1.3.71) (judge verdict: Accepted)

fun main(){
    val s = readLine()!!.toString()
    val n = s.length

    fun palindrome(s: String): Boolean{
//        println(s)
//        println(s.length)
        for(i in 0 .. (s.length-1)/2){
            if(s[i] != s[s.length - 1 - i])
                return false
        }
        return true
    }

    //substring; 終了インデックスの１つ前までで切る
    if(
            palindrome(s) &&
            palindrome(s.substring(0, (n - 1)/2)) &&
            palindrome(s.substring((n + 3)/2 - 1   , n))
    ) println("Yes")
    else println("No")
}