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>

#define rep(i, n) for(int (i) = 0; i < (n); ++(i))

using ll = long long int;
const ll MOD = 1e9 + 7;

int main() {
  std::string S;
  std::cin >> S;

  int N = (int) S.length();
  std::string sub1, rsub1, sub2, rsub2;
  sub1 = S.substr(0, N / 2);
  rsub1 = std::string(sub1);
  std::reverse(rsub1.begin(), rsub1.end());

  sub2 = S.substr(N / 2 + 1);
  rsub2 = std::string(sub2);
  std::reverse(rsub2.begin(), rsub2.end());

  if(sub1 == rsub1 && sub2 == rsub2) {
    std::cout << "Yes" << '\n';
  } else {
    std::cout << "No" << '\n';
  }


}