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;
using ll = long long;

int kaibun(string s) {
  int N;
  int ans = 1;
  N = s.size();
  if (N%4!=3) {
    ans *= 0;
  } else {
    for (int i = 0; i < (N-1)/2; i++) {
      if (s.at(i)==s.at(N-i-1)) {
        ans *= 1;
      } else {
        ans *= 0;
      }
    }
  }
  return ans;
}

int main() {
  string s, s1, s2;
  cin >> s;
  int n;
  n = s.size();
  s1 = s.substr(0, (n-1)/2);
  s2 = s.substr((n+1)/2, (n-1)/2);
  
  if (kaibun(s)==1 && kaibun(s1)==1 && kaibun(s2)==1) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}