6.2 strelka

using System;

public class Program
{
    public static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        Console.Write(new String('.', n/2));
        Console.Write(new String('#',n));
        Console.WriteLine(new String('.', n/2));
        for(int i = 0; i < n - 2; i++)
        {
            Console.Write(new String('.', n/2));
            Console.Write("#");
            Console.Write(new String('.', n - 2));
            Console.Write("#");
            Console.WriteLine(new String('.', n/2));
        }
        Console.Write(new String('#', n / 2 + 1));
        Console.Write(new String('.', n - 2));
        Console.WriteLine(new String('#', n / 2 + 1));
        for(int i = 1; i <= n - 2; i++)
        {
            Console.Write(new String('.', i));
            Console.Write('#');
            Console.Write(new String('.', n * 2 - (i * 2 ) - 3));
            Console.Write('#');
            Console.WriteLine(new String('.', i));
        }
        Console.Write(new String('.', n - 1));
        Console.Write("#");
        Console.WriteLine(new String('.', n - 1));
    }
}