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<stack>
#include<string>

using namespace std;

bool isParindrome(string input) {
  auto left = input.begin();
  auto right = input.end()-1;
  while(left < right) {
    if (*left++ != *right--) return false;
  }
  return true;
}

int main() {
  string input = "hoohaahooh";
  string first = input.substr(0, (input.size()-1)/2);
  string second = input.substr( (input.size()+3)/2 - 1 );
  bool res = isParindrome(first) && isParindrome(second);
  if (res) cout << "YES" << endl;
  else cout << "NO" << endl;
}