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<bits/stdc++.h>
#define rep(i,n) for(int i=0; i<(n); ++i)
#define all(x) (x).begin(),(x).end()
#define pb push_back
using namespace std;
using ll = long long;
using P = pair<int,int>;
int main()
{
  string s;
  cin >> s;

  bool flg = true;
  string t = s;
  reverse(all(t));

  if(s != t) flg = false;
  int n = s.size();
  for(int i=0; i<(n-1)/2; i++){
    if(s[i] != s[(n-1)/2 - i - 1]) flg = false;
  }
  //cout << flg << endl;
  for(int i=(n+3)/2; i<n; i++){
    if(s[i-1] != s[n - i]) flg = false;
  }

  if(flg) printf("Yes");
  else printf("No");
}