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>

int main(void){
    char str1[100];
    int i,n,k=0;
    for(i=0;i<100;i++){
        str1[i]=0;
    }
    scanf("%s",str1);
    for(i=0;i<99;i++){
        if(str1[i]==0){
            n=i;
            break;
        }
    }
    printf("%s\nn=%d\n",str1,n);
    for(i=0;i<(n-1)/4;i++){
        if(str1[i]==str1[(n-1)/2-i-1]){
            k++;
        }
    }
    for(i=0;i<(n-3)/4;i++){
        if(str1[(n+3)/2+i-1]==str1[(n-1)-i]){
            k++;
        }
    }
    if(k==(n-3)/2){
        printf("Yes");
    }else{
        printf("No");
    }
    return 0;
}