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# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

public class Test
{
    public static void Main()
    {
        //入力
        string R = Console.ReadLine();

        string result = "No";

        if (Kbn(R))
        {
            int N = R.Count();

            string jk2 = R.Substring(0, ((N - 1) / 2));
            if (Kbn(jk2))
            {
                string jk3 = R.Substring(((N - 1) / 2)-1,N );
                if (Kbn(jk3))
                {
                    result = "Yes";
                }
            }
        }


        System.Console.WriteLine(result);
    }

    //回文判定
    private static bool Kbn(string str_1) 
    {
        char[] R = str_1.ToCharArray();

        string str_ = string.Join("", R);

        Array.Reverse(R);
        string restr = string.Join("", R);

        if (restr == str_)
        {
            return true;
        }
        else { return false; }
    
    }

}