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

int main()
{
    char s[100];
    scanf("%s",s);
    
    int len = strlen(s);
    
    char s_l[50], s_r[50];
    for( int i=0; i<len/2; i++ ){
        s_l[i] = s[i];
        s_r[i] = s[len-i-1];
    }
    
    if( pari(s, len) && pari(s_r, len/2) && pari(s_l, len/2) ){
        printf("Yes\n");
    } else {
        printf("No\n");
    }
    
    return 0;
}