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 s[100];
  scanf("%s", &s);
  
  int n;
  n = strlen(s);
  
  int i = 0;
  int k = n - 1;
  while (i < n / 2)
  {
    if (s[i] != s[k])
    {
      printf("No");
      return 0;
    }
    i++;
    k--;
  }
  
  int s2, s3;
  s2 = (n - 1) / 2 - 1;
  s3 = (n + 3) / 2 - 1;
  i = 0;
  k = n - 1;
  while (i < n / 2)
  {
    if (s[i] != s[s2] || s[s3] != s[k])
    {
      printf("No");
      return 0;
    }
    i++;
    s2--;
    s3++;
    k--;
  }
  
  printf("Yes");
  return 0;
}