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 <string.h>

int main()
{
    char s[100];
    scanf("%s", s);

    int len  = strlen(s);
    int i, flag, flag1, flag2, temp = len / 2, count;
    flag = 1;
    for(i = 0; i < len/2; i++){
        if(s[i] != s[len - i - 1]){
            flag = 0;
            break;
        }
    }
    if(flag){
        flag1 = 1, flag2 = 1, count = 0;
        for(i = 0; count <= temp / 2; count++, i++){
            if(s[i] != s[(len-1) / 2 - i - 1]){
                flag1 = 0;
                //printf("flag1 = 0 at i = %d\n", i);
                break;
            }
        }
        count = 0;
        for(i = (len + 3) / 2; count <= temp / 2; count++, i++){
            if(s[i] != s[len - i - 1]){
            flag2 = 0;
            break;
            }
        }
        //printf("flag1 = %d, flag2 = %d", flag1, flag2);

        if(flag1 && flag2) printf("YES\n");
        else printf("NO\n");
    }
    else printf("NO\n");

    return 0;
}