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 i, n, ans=0;

  scanf("%s", s);
  for(n=0;s[n]!='\0';n++);
  for(i=0;i<n/2;i++){
    if(s[i]!=s[n-1-i]){
      ans=1;
      break;
    }
  }
  if(ans==0){
  for(i=0;i<(n-1)/2/2;i++){
    if(s[i]!=s[(n-1)/2-1-i]){
	ans=1;
	break;
    }
  }
  }
  if(ans==0){
  for(i=(n+3)/2-1;i<((n+3)/2+n)/2;i++){
    if(s[i]!=s[n-1-i]){
      ans=1;
      break;
    }
  }
  }

  if(ans==0)
  printf("Yes\n");
  if(ans==1)
    printf("No\n");

  return 0;
}