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<iomanip>
#include<string>
#include<queue>
#include<vector>
#include<algorithm>
#include<tuple>
#include<numeric>
#include<map>
#include<cmath>
#define ll long long
#define rep(i,n) for(int i=0;i<(int) (n);i++)
ll gcd(ll a,ll b){return b ? gcd(b,a%b) : a;}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
using namespace std;
bool s_check(string s){
  string t(s.rbegin(),s.rend());
  return s==t;
}
int main(){
  string s;
  cin>>s;
  int n=s.size();
  if(s_check(s) && s_check(s.substr(0,(n-1)/2)) && s_check(s.substr((n+1)/2))){
      cout<<"Yes";
  }
  else cout<<"No";

  return 0;
}