vol.1

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

namespace Triangle
{
    class Program
    {
        static void Main(string[] args)
        {
            int size = int.Parse(Console.ReadLine());
            int point = 1;
            int sharp = (4 * size - 2) / 2;
            int empty = 1;
            Console.WriteLine(new string ('#', (4 * size + 1)));
            for (int row = 1; row <= size; row++)
            {
                if (row == (size / 2 + 1))
                {
                    Console.Write(new string('.', point));
                    Console.Write(new string('#', sharp));
                    Console.Write(new string(' ', empty / 2 - 1));
                    Console.Write("(@)");
                    Console.Write(new string(' ', empty / 2 - 1));
                    Console.Write(new string('#', sharp));
                    Console.Write(new string('.', point));
                    sharp-=2;
                    point++;
                    empty+= 2;
                    Console.WriteLine();
                }
                else
                {
                    Console.Write(new string('.', point));
                    Console.Write(new string('#', sharp));
                    Console.Write(new string(' ', empty));
                    Console.Write(new string('#', sharp));
                    Console.Write(new string('.', point));
                    point++;
                    sharp -= 2;
                    empty += 2;
                    Console.WriteLine();
                }
            }
            sharp = (4 * size - 2) / 2;
            for (int row = 1; row <= size; row++)
            {
                Console.Write(new string('.', point));
                Console.Write(new string('#', sharp));
                Console.Write(new string('.', point));
                point++;
                sharp-= 2;
                Console.WriteLine();
            }
        }
    }
}