
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;


namespace StartFinish
{
 
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                int[] hw = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();


                if (hw[0] == 0 && hw[1] == 0)
                {
                    break;
                }
                int tmp = 0;
                for(int i = 0; i < hw[0]; i++)
                {
                    for (int j = 0; j < hw[1]; j++)
                    {
                        if (tmp % 2 == 0)
                        {
                            Console.Write("#");
                        }
                        else
                        {
                            Console.Write(".");
                        }
                        tmp++;
                    }
                    if (hw[0] % 2 == 0)
                    {
                        tmp++;
                    }
                    Console.WriteLine();
                }
                Console.WriteLine();
              
            }
        }
    }
}