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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC159B
{
    class Program
    {
        static void Main(string[] args)
        {
            string S = Console.ReadLine();
            int N = S.Length;
            int a = 1;
            int b = (N - 1) / 2;
            int c = (N + 3) / 2;
            int d = N;
            bool hantei = true;
            if (N == 3)
            {
                if (S[a-1] != S[d-1])
                {
                    hantei = false;
                }
            }
            else
            {
                while (a <= (N - 1) / 2)
                {
                    if (S[a-1] == S[b-1]& S[a-1] == S[c-1] & S[a-1] == S[d-1])
                    {
                    }
                    else
                    {
                        hantei = false;
                    }
                    a += 1;
                    b -= 1;
                    c += 1;
                    d -= 1;
                }
            }
            if (hantei == true)
            {
                Console.WriteLine("Yes");
            }
            else
            {
                Console.WriteLine("No");
            }
        }
    }
}