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: Wrong Answer)

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

bool pal(string& s){
	int l = 0, r = s.size()-1;
  while(l<r){
  	if (s[l]!=s[r]){return false;}
    l++;r--;
  }
  return true;
}

int main(){
  string s;cin>>s; int n = s.size();
  string s1 = s.substr(0,(n-1)/2-1), s2 =s.substr((n+3)/2-1, n-(n+3)/2+1); 
	bool ans = pal(s) && pal(s1) && pal(s2);
  cout<<(ans?"Yes":"No")<<endl;
}