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<stdlib.h>
#include<string.h>

int main(void)
{
    int i,j,N;
    char str[99];
    int flag = 1;

    scanf("%s",str);
    N = strlen(str);

    if(N == 3)
        printf("Yes");

    else
    {
        for(i=0;i<(N-1)/4;i++)
        {
            if(str[i] != str[(N-1)/2-1-i])
            {
                flag = 0;
                break;
            }
        }

        for(i=(N+3)/2-1; i< (N+3)/2-1 + (N-(N+3)/2+1)/2; i++)
        {
            if(str[i] != str[N-1-i])
            {
                flag = 0;
                break;
            }
        }

        if(flag)
            printf("Yes");
        else
            printf("No");
        
    }
    return 0;
}