//ITP1_5_C
//

using System;
using System.Collections.Generic;



class Program
{
    static void Main(string[] args)
    {
        int[] h = new int[50];
        int[] w = new int[50];

        int count = 0, sw = 0;

        while (true)
        {
            //?????????????????????????????????int??????iaaray????????????????????\

            int[] iarray = Array.ConvertAll<string, int>((Console.ReadLine().Split(' ')), delegate (string value)
            {
                return int.Parse(value);
            });

            h[count] = iarray[0];
            w[count] = iarray[1];

            if (h[count] == 0 && w[count] == 0)
                break;
            count++;

        }

        for (int c = 0; c < count; c++)
        {
            for (int i = 0; i < h[c]; i++)
            {
                for (int j = 0; j < w[c]; j++)
                {                   
                                                //sw???o??¨1??§?????¨.?????¶???
                    if (sw == 0)
                    {
                        Console.Write("#");
                        sw = 1;
                    }
                    else
                    {
                        Console.Write(".");
                        sw = 0;
                    }
                }
                Console.Write("\r\n");
                if ((h[c] % 2 == 1 || w[c] % 2 == 0) && w[c] != 1)
                    sw = 1;
            }
            Console.Write("\r\n");
            sw = 0;
        }

    }
}