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>
#include<string.h>

int main()
{
    char str[99];
    gets(str);
    int n=0;
    n=strlen(str);
    int i,j,x,y=0,z=0;
    x=(n-1)/2;
    for (i=0,j=n-1;i<n/2;i++,j--)
    {
        if (str[i]==str[j])
            z++;
        else
        {
            printf("No\n");
           break;
        }
    }
    if (z==(n/2))
    {
        for (i=0,j=x-1;i<x/2;i++,j--)
        {
            if (str[i]==str[j])
                y++;
            else
            {
                printf("No\n");
                break;
            }
        }
    }

    if (y==(x/2))
        printf("Yes\n");
    return 0;
}