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++ (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <string>


using namespace std;

bool rev(string s) {
   int N = s.length();

   for(int i = 0; i < N / 2; i++) {
      if(s[i] != s[N - i - 1]) {
         return false;
      }
   }

   return true;
}
   

int main ()  {
   string S; cin >> S;

   bool rev1 = rev(S);

   int N = S.length();
   string s1;
   for(int i = 0; i < (N - 1) / 2; i++) {
      s1 = S[i];
   }

   string s2;
   for(int i = (N + 3) / 2; i < N; i++) {
      s2 = S[i];
   }

   bool rev2 = rev(s1);
   bool rev3 = rev(s2);

   if(rev1 && rev2 && rev3) {
      cout << "Yes" << endl;
   } else {
      cout << "No" << endl;
   }
}