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>
typedef long long ll;
#define rep(i,n) for(ll i = 0; i < (n); ++i )
#define rep_rev(n,i) for(ll i = n; i >= 0; --i )
using namespace std;
using P = pair<int, int>;
const long long INF = 1LL << 60;

int main(){
  string s; cin >> s;
  int N = s.length();
  rep(i,(N-1)/2){
    if(s[i] != s[((N-1)/2) - 1 - i]) {
      cout << "No" << endl;
      return 0;
    }
  }
  for(int i = ((N+3)/2) - 1; i < N; ++i){
    if(s[i] != s[N-1-i]){
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
  return 0;
}