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: Wrong Answer)

package main

import (
	"fmt"
)

func main() {
	var s string
	fmt.Scanf("%s", &s)
	n := len(s)
	if isPalindrome(s) && isPalindrome(s[0:(n-1)/2]) && isPalindrome(s[(n+3)/2-1:n]) {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}

func isPalindrome(s string) bool {
	r := []rune(s)
	n := len(r)
	var mid int
	var f, b []rune
	if n % 2 == 1 {
		mid = (n - 1) / 2
		f = append([]rune{}, r[0:mid]...)
		b = append([]rune{}, r[mid+1:n]...)
	} else {
		mid = n / 2
		f = append([]rune{}, r[0:mid]...)
		b = append([]rune{}, r[mid:n]...)
	}

	fmt.Printf("f=%s, b=%s, mid=%d\n", string(f), string(b), mid)
	for i := 0; i < mid; i++ {
		if f[i] != b[mid-1-i] {
			return false
		}
	}
	return true
}