using System;
using System.Text.RegularExpressions;

namespace AizuOnLine
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                string[] data = Console.ReadLine().Split(' ');
                int h = Convert.ToInt32(data[0]);
                int w = Convert.ToInt32(data[1]);

                if (h == 0 && w == 0) { break; }

                bool flag = true;
                for (int x = 0; x < h; x++)
                {
                    string sharp = new string('#', w);

                    if (flag)
                    {
                        Console.WriteLine(Regex.Replace(sharp, "##", "#."));
                    }
                    else
                    {
                        Console.WriteLine(Regex.Replace(sharp, "##", ".#"));
                    }

                    flag = !flag;
                }

                Console.WriteLine(string.Empty);
            }
        }
    }
}