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 Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

func main() {
	var S string
	fmt.Scanf("%s", &S)

	if isKaibun(S) && isKaibun(S[0:(len(S)-1)/2]) && isKaibun(S[(len(S)+3)/2-1:]) {
		fmt.Println("Yes")
		return
	}

	fmt.Println("No")
}

func isKaibun(s string) bool {
	for i := 0; i < len(s)/2; i++ {
		if s[i] != s[len(s)-1-i] {
			return false
		}
	}
	return true
}