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)

#include <stdio.h>

int main(void)
{
	char s[99];
	int n;
	int i;

	scanf("%s", s);

	n = 0;

	/* 文字数を数える。 */
	while (s[n] != '\0')
	{
		n++;
	}
	
	/* sが回文であるかどうか調べる。 */
	for (i = 0; i  < n / 2; i ++)
	{
		if (s[i] != s[n -1 - i])
		{
			printf("No\n");
			return 0;
		}
	}

	/* s全体が回文なので、前半のみ回文かどうか調べる。 */
	for (i = 0; i < (n - 1) / 4; i++)
	{
		if (s[i] != s[n / 2 - 1 - i])
		{
			printf("No\n");
			return 0;
		}
	}

	printf("Yes\n");

	return 0;
}