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 <bits/stdc++.h>
using namespace std;

int main() {
    string S;
    cin >> S;
    int N = S.size();

    bool ok1, ok2, ok3;
    string T = S;
    reverse(T.begin(), T.end());
    if (S == T) {
        ok1 = true;
    }
    string U = S.substr(0, (N - 1) / 2);
    string V = U;
    reverse(U.begin(), U.end());
    if (U == V) {
        ok2 = true;
    }
    string W = S.substr((N + 1) / 2, U.size());
    reverse(W.begin(), W.end());
    string X = W;
    if (W == X) {
        ok3 = true;
    }

    if (ok1 && ok2 && ok3) {
        cout << "Yes" << endl;
    }
    else {
        cout << "No" << endl;
    }
}