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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
 
int main(void)
{
  int i, j;
  char aa[99+2];
  char a,b;
  int len=0, cnt;
  scanf("%s", aa);
  len=strlen(aa);
//  printf("aa %d %d %d %s\n",len,(len-1)/2/2,(len+3)/2,aa);
  for (i = 0; i < len/2; i++){
    a = aa[i];
    b = aa[len-1 - i];
//    printf("a %c  b %c\n",a,b);
    if(a !=b ){
      printf("No\n");
      return 0;
    }
  }
  cnt=(len-1)/2-1;
  for (i = 0; i < cnt; i++){
    a = aa[i];
    b = aa[cnt - i];
//    printf("a %c  b %c\n",a,b);
    if(a !=b ){
      printf("No\n");
      return 0;
    }
  }
  char cnt2=(len+3)/2-1;
  for (i = 0; i < cnt; i++){
    a = aa[i+cnt2];
    b = aa[cnt - i + cnt2];
//    printf("a %c  b %c\n",a,b);
    if(a !=b ){
      printf("No\n");
      return 0;
    }
  }
  printf("Yes\n");
  return 0;
 
}