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: Accepted)

#include <iostream>
#include <string>
using namespace std;

bool check(string s, int n) {
  for(int i  =0; i < n/2; i++) {
    if(s[i] != s[n-1-i]) return false;
  }
  return true;
}

int main() {
  string S; cin >> S;
  int N = S.size();
  bool ok = true;
  if(!check(S, N)) ok = false;
  string s1, s2;
  s1 = S.substr(0, (N-1)/2);
  if(!check(s1, s1.size())) ok = false;
  s2 = S.substr((N+3)/2-1);
  if(!check(s2, s2.size())) ok = false;
  cout << (ok ? "Yes" : "No") << endl;
  return 0;
}