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

namespace _1_5_C
{
    class Program
    {
        static void Main(string[] args)
        {
            for(int i=1;　i>0 ; i++)
            {
                string[] str = Console.ReadLine().Split(' ');
                int H = int.Parse(str[0]);
                int W = int.Parse(str[1]);
                // Wが偶数、奇数の時で場合分け
                if (W == 0 && H == 0) break;
                else if (W == 1 && H == 1)
                {
                    Console.Write("#");
                    Console.Write("\n");
                }
                else if (W % 2 == 0 && H % 2 == 0)
                {
                    for (int g = 0; g < H / 2; g++)
                    {
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write("#.");
                        }
                        Console.Write("\n");
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write(".#");
                        }
                        Console.Write("\n");
                    }
                }
                else if (W % 2 == 0 && H % 2 == 1)
                {
                    for (int g = 0; g < H / 2; g++)
                    {
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write("#.");
                        }
                        Console.Write("\n");
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write(".#");
                        }
                        Console.Write("\n");
                    }
                    for (int j = 0; j < W / 2; j++)
                    {
                        Console.Write("#.");
                    }
                    Console.Write("\n");
                }
                else if (W % 2 == 1 && H % 2 == 0)
                {
                    for (int g = 0; g < H / 2; g++)
                    {
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write("#.");
                        }
                        Console.Write("#");
                        Console.Write("\n");
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write(".#");
                        }
                        Console.Write(".");
                        Console.Write("\n");
                    }
                }
                else if (W % 2 == 1 && H % 2 == 1)
                {
                    for (int g = 0; g < H / 2; g++)
                    {
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write("#.");
                        }
                        Console.Write("#");
                        Console.Write("\n");
                        for (int j = 0; j < W / 2; j++)
                        {
                            Console.Write(".#");
                        }
                        Console.Write(".");
                        Console.Write("\n");
                    }
                    for (int j = 0; j < W / 2; j++)
                    {
                        Console.Write("#.");
                    }
                    Console.Write("#");
                    Console.Write("\n");
                }
                Console.Write("\n");
            }
        }
    }
}



Measured memory_bytes: 15860