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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>

int count(char *str) {
    int i = 0;
    while (str[i] != '\0') {
        i++;
    }
    return i;
}

int judge(char *str, int start, int end) {
    while (start < end) {
        if (str[start] != str[end]) {
            return 0;
        }
        start++;
        end--;
    }
    return 1;
}

int main(void)
{
    char S[101];
    int strNum;
    int center;
    int result = 0;

    // input
    scanf("%s", S);

    strNum = count(S);
    center = strNum / 2;

    result = judge(S, 0, strNum - 1);
    result += judge(S, 0, center - 1);
    result += judge(S, center + 1, strNum - 1);

    // output
    if (result == 3) {
        printf("Yes\n");
    } else {
        printf("No\n");
    }

    return 0;
}