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: Wrong Answer)

#include <stdio.h>
#include <string.h>

int main(void)
{
	char s[101];  
	int i;
  
    scanf("%s", s);
    int n = strlen(s);

    int f1 = 1;
  	int f2 = 1;
  
    for (i=0; i<n/4; i++) {
      if (s[i]!=s[n/2-1-i]) {
        f1 = 0;
        break;
      }
      
      if (s[i+n/2+1]!=s[n-1-i]) {
        f2 = 0;
      	break;
      }
    }
  
    if (f1 && f2)
      printf("Yes\n");
  
    else
      printf("No\n");
  
    return 0;
}