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

namespace ConsoleApplication30
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                var ab = Console.ReadLine().Split().Select(int.Parse).ToArray();
                int a = ab[0];
                int b = ab[1];
                {
                    if (a == 0 && b == 0)
                        break;

                    {
                        for (int c = 1; c <= a; c++)
                        {

                            for (int d = 1; d <= b; d++)
                            {
                                if ((c + d) % 2 == 0)
                                {
                                    Console.Write("#");
                                }
                                else
                                {
                                    Console.Write(".");
                                }


                            }
                            Console.WriteLine();
                        }
                    }
                }
            }
        }
    }
}