using System;
using System.Collections.Generic;
using System.Linq;

class aizu_judge
{
    static void Main(string[] args)
    {
        while(true)
        {
            int[] num = Console.ReadLine().Split().Select(int.Parse).ToArray();

            //int[] num = new int[] {3,4};
            if (num[0] + num[1] == 0)
                break;


            for (int i = 1; i <= num[0]; i++)
            {
                string width = string.Empty;
                string a = string.Empty;
                string b = string.Empty;

                if(i % 2 == 0)
                {
                    a = ".";
                    b = "#";
                }
                else
                {
                    a = "#";
                    b = ".";
                }

                if(num[1] > 1 && num[1] % 2 == 0)
                {
                    width = string.Concat(Enumerable.Repeat(a + b, num[1] / 2));
                }
                else if (num[1] > 1 && num[1] % 2 > 0)
                {
                    width = string.Concat(Enumerable.Repeat(a + b, num[1] / 2)) + a;
                }
                else
                {
                    width = a;
                }
                
                Console.WriteLine(width);
            }
            Console.WriteLine();
        }
    }
}