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# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
 
namespace Sample
{
  class Sample
  {
    static void Main(string[] args)
    {
    string s=Console.ReadLine();
    int N=s.Length;
    int flg=0;
      for(int i=0;i<N/2-1;i++){
        if(s.Substring(i,0)!=s.Substring(N-1-i,0)){
          flg=1;
          break;
        }
      }
      if(flg!=1){
    for(int j=0;j<(N-1)/2-1;j++){
          if(s.Substring(j,0)!=s.Substring((N-1)/2-1-j,0)){
          flg=1;
          break;
          }
        }
    
     for(int k=(N+3)/2-1;k<(N-(N+3)/2)/2-1;k++){
          if(s.Substring((N+3)/2-1+k,0)!=s.Substring((N-1)/2-1-k,0)){
          flg=1;
          break;
        }   
             }
    }
             if(flg==1){
               Console.WriteLine("No");
             }else
             {Console.WriteLine("Yes");
             }
    }
    
  }

}