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++ (GCC 9.2.1) (judge verdict: Accepted)

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

string S;
int n, b, e;

int main(void) {
  cin >> S;
  n = S.size();

  b = 0;
  e = n - 1;
  while (b < e) {
    if (S[b++] != S[e--]) {
      cout << "No" << endl;
      return 0;
    }
  }

  b = 0;
  e = (n - 1) / 2 - 1;
  while (b < e) {
    if (S[b++] != S[e--]) {
      cout << "No" << endl;
      return 0;
    }
  }

  b = (n + 3) / 2 - 1;
  e = n - 1;
  while (b < e) {
    if (S[b++] != S[e--]) {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
  return 0;
}