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>
#include <string.h>

int	main	(void)
{

	char str[101];
	scanf("%s",str);
	int len = strlen(str);
	int index =0;
	while (index < len/2)
	{
		if(str[index] != str[len-index-1])
		{
			printf("No");
			return (0);
		}
		index++;
	}
	if (len ==3)
	{
		printf("Yes\n");
		return (0);
	}
	index =0;
	while (index< (len-1)/4)
	{
		if(str[index] != str[(len-1)/2 - index -1])
		{
			printf("No");
			return (0);
		}
		index++;
	}
	index =0;
	while (index< (len-1)/4)
	{
		if(str[len -index-1] != str[len -((len-1)/2 - index -1)-1])
		{
			printf("No");
			return (0);
		}
		index++;
	}
	printf("Yes\n");
	return (0);
}