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 C (GCC 5.4.1) (judge verdict: Accepted)

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>  
#include <stdlib.h> 
#include <string.h> 


int check() {
	char a[105];
	int len;

	scanf("%s", &a);
	len = strlen(a);

	// i 文字目と len-i-1文字目 が違ったら回文ではない
	for (int i = 0; i < len; i++)
	{
		if (a[i] != a[len - i - 1]) return 0;
	}
	// 前半部について、i文字目と(len/2)-i-1文字目が違ったら回分ではない
	for (int i = 0; i < len / 2; i++)
	{
		if (a[i] != a[len / 2 - i - 1]) return 0;
	}
	// 後半部について、回文だったら前半部と同じ文字なので調べないで良い
	//強い回文だったらtrueを返す
	return 1;
}

int main()
{
	if (check()) printf("Yes\n");
	else printf("No\n");
	return 0;
}