Exam July Evening 3. House with a Window

using System;

public class HouseWithAWindow
{
    public static void Main()
    {
        checked
        {
            int num = int.Parse(Console.ReadLine());

            int width = (2 * num) - 1;
            int outerDots = num - 1;
            string outerDotSeq = new string('.', outerDots);
            Console.WriteLine("{0}*{0}", outerDotSeq);
            int innerDots = 1;
            string innerDotSeq;
            for (int row = 1; row < num; row++)
            {
                outerDots--;
                outerDotSeq = new string('.', outerDots);
                innerDotSeq = new string('.', innerDots);
                Console.WriteLine("{0}*{1}*{0}", outerDotSeq, innerDotSeq);
                innerDots += 2;
            }

            Console.WriteLine(new string('*', width));

            innerDotSeq = new string('.', width - 2);
            string innerAsteriskSeq = new string('*', num - 3);
            outerDots = num / 2;
            outerDotSeq = new string('.', outerDots);
            for (int row = 0; row < num; row++)
            {
                if (row < (num / 4) || row >= (num * 3) / 4)
                {
                    Console.WriteLine("*{0}*", innerDotSeq);
                }
                else
                {
                    Console.WriteLine("*{0}{1}{0}*", outerDotSeq, innerAsteriskSeq);
                }
            }

            Console.WriteLine(new string('*', width));
        }
    }
}