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 str_count(char *str){
  int i = 0;
  while(str[i] != '\0'){
    i++;
  }
  
  return i;
}

int is_palindrome(char *str, int a, int b){
  for(int i = 0;i <= (a + b) / 2 - a;i++){
    if(str[a + i] != str[b - i]){
      return 0;
    }
  }
  return 1;
}

int main(){
  int n, flag = 0;
  char str[100];
  
  scanf("%s", str);
  
  n = str_count(str);
  
  if(is_palindrome(str, 0, (n - 1) / 2 - 1)){
    if(is_palindrome(str, (n + 3) / 2 - 1 , n - 1)){
      if(is_palindrome(str, 0, n - 1)){
        flag = 1;
      }
    }
  }
 
  if(flag == 1){
    printf("Yes");
  }
  else{
    printf("No");
  }

  
  return 0;
  
}