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)
{
    int i;
    char S[100];
    scanf("%s", S);
    for(i = 0; S[i]!='\0'; ++i);
    if(i % 2 == 0) printf("No\n");
    else {
        int L, LL, LR, a, RL, RR, b, R, m = 0;
        a = i - 1;
        L = a / 2;
        R = L + 2;
        b = L / 2;
        for(int j = 0; j < b; j ++){
            LL = j; LR = L - j - 1; RL = R + j - 1; RR = i - j - 1;
            if(S[LL] == S[LR]){
                if(S[RL] == S[RR]){
                    if(S[LL] == S[RL]) m++;
                };
            };
        };
        if(m == b) printf("Yes\n");
        else printf("No\n");
    };

    return 0;
}