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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <string>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
    string S;
    int N;

    cin >> S;

    string Answer = "No";

    N = S.size();

    int AS = (N - 1) / 2;
    int BS = (N + 3) / 2;

    string A = S.substr(0, AS);
    string B = S.substr(BS - 1, N);

    string AA = S.substr(0, AS);
    string BB = S.substr(BS - 1, N);

    // 反転
    reverse(AA.begin(), AA.end());
    reverse(BB.begin(), BB.end());

    if (A == AA && B == BB)
    {

        Answer = "Yes";
    }

    cout << Answer << endl;
}