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 = readString()
    if (
        s.isPalindrome() &&
        s.substring(0 until (s.length - 1) / 2).isPalindrome() &&
        s.substring((s.length + 3) / 2 - 1 until s.length).isPalindrome()
    ) {
        println("Yes")
    } else {
        println("No")
    }
}

fun String.isPalindrome(): Boolean {
    return if (this.length % 2 == 0) {
        val x = this.substring(0 until this.length / 2)
        val y = this.substring(this.length / 2 until this.length).reversed()
        x == y
    } else {
        val x = this.substring(0 until (this.length - 1) / 2)
        val y = this.substring((this.length + 3) / 2 - 1 until this.length).reversed()
        x == y
    }
}

// Tools
fun readString() = readLine()!!
fun readInt() = readLine()!!.toInt()
fun readLong() = readLine()!!.toLong()
fun readStringList() = readLine()!!.split(" ")
fun readIntList() = readLine()!!.split(" ").map(String::toInt)
fun readLongList() = readLine()!!.split(" ").map(String::toLong)