DrawButterfly

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

// https://judge.softuni.bg/Contests/Practice/Index/179#4

namespace DrawButterfly
{
    public class Program
    {
        public static void Main()
        {
            int n = int.Parse(Console.ReadLine());

            int sideWidth = n - 1;
            int halfPartHeight = n - 2;

            // Drawing first part
            for (int rowIndex = 0; rowIndex < halfPartHeight; rowIndex++)
            {
                char symbol = '*';
                if (rowIndex % 2 != 0)
                {
                    symbol = '-';
                }

                // Left side
                string rowOutput = "";
                for (int i = 0; i < sideWidth - 1; i++)
                {
                    rowOutput += symbol;
                }

                rowOutput += "\\ /";

                // Right side
                for (int i = 0; i < sideWidth - 1; i++)
                {
                    rowOutput += symbol;
                }

                // Draw row string
                Console.WriteLine(rowOutput);
            }

            // Draw middle row
            string middleRow = "@";
            for (int i = 0; i < sideWidth; i++)
            {
                middleRow = " " + middleRow;
            }

            for (int i = 0; i < sideWidth; i++)
            {
                middleRow = middleRow + " ";
            }

            // Draw middle row
            Console.WriteLine(middleRow);

            // Drawing second part
            for (int rowIndex = 0; rowIndex < halfPartHeight; rowIndex++)
            {
                char symbol = '*';
                if (rowIndex % 2 != 0)
                {
                    symbol = '-';
                }

                // Left side
                string rowOutput = "";
                for (int i = 0; i < sideWidth - 1; i++)
                {
                    rowOutput += symbol;
                }

                rowOutput += "/ \\";

                // Right side
                for (int i = 0; i < sideWidth - 1; i++)
                {
                    rowOutput += symbol;
                }

                // Draw row string
                Console.WriteLine(rowOutput);
            }
        }
    }
}