Exam 6. Arrow

namespace _3.Arrow
{
    using System;

    public class Arrow
    {
        public static void Main(string[] args)
        {
            checked
            {
                int numN = int.Parse(Console.ReadLine());

                int lenghtIntDotSeq = numN - 2;
                string internalDotSeq = new string('.', lenghtIntDotSeq);
                int lenghtExtDotSeq;
                string externalDotSeq;
                for (int row = 1; row < numN; row++)
                {
                    lenghtExtDotSeq = numN / 2;
                    externalDotSeq = new string('.', lenghtExtDotSeq);
                    if (row == 1)
                    {
                        string topSeq = new string('#', numN);
                        Console.WriteLine("{0}{1}{0}", externalDotSeq, topSeq);
                    }
                    else
                    {
                        Console.WriteLine("{0}#{1}#{0}", externalDotSeq, internalDotSeq);
                    }
                }

                string middleDsSeq = new string('#', (numN / 2) + 1);
                Console.WriteLine("{0}{1}{0}", middleDsSeq, internalDotSeq);

                int maxLenghtRow = (numN * 2) - 1;
                for (int row = 1; row < numN; row++)
                {
                    if (row == numN - 1)
                    {
                        externalDotSeq = new string('.', (numN / 2) * 2);
                        Console.WriteLine("{0}#{0}", externalDotSeq);
                    }
                    else
                    {
                        externalDotSeq = new string('.', row);
                        lenghtIntDotSeq = maxLenghtRow - (2 * row) - 2;
                        internalDotSeq = new string('.', lenghtIntDotSeq);
                        Console.WriteLine("{0}#{1}#{0}", externalDotSeq, internalDotSeq);
                    }
                }
            }
        }
    }
}