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

namespace AOJ1_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]);
                if (H == 0 && W == 0)
                { break; }
                else if (H == 1 && W == 1)
                {
                    Console.Write("#");
                    Console.Write("\n");
                }
                else if (H == 1)
                {
                    for (int h = 0; h <= H / 2; h++)
                    {
                        if (W % 2 == 0)
                        {
                            for (int w = 0; w < (W / 2); w++)
                            {
                                Console.Write("#");
                                Console.Write(".");
                            }
                            Console.Write("\n");
                        }
                        else
                        {
                            for (int w = 0; w < (W / 2); w++)
                            {
                                Console.Write("#");
                                Console.Write(".");
                            }
                            Console.Write("#");
                            Console.Write("\n");
                        }
                    }
                }
                else
                {
                    if (H % 2 == 0)
                    {
                        for (int h = 0; h < H / 2; h++)
                        {
                            if (W % 2 == 0)
                            {
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write("#");
                                    Console.Write(".");
                                }
                                Console.Write("\n");
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write(".");
                                    Console.Write("#");
                                }
                                Console.Write("\n");
                            }
                            else
                            {
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write("#");
                                    Console.Write(".");
                                }
                                Console.Write("#");
                                Console.Write("\n");
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write(".");
                                    Console.Write("#");
                                }
                                Console.Write(".");
                                Console.Write("\n");
                            }
                        }
                    }
                    else
                    {
                        for (int h = 0; h < (H / 2); h++)
                        {
                            if (W % 2 == 0)
                            {
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write("#");
                                    Console.Write(".");
                                }
                                Console.Write("\n");

                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write(".");
                                    Console.Write("#");
                                }
                                Console.Write("\n");
                            }
                            else
                            {
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write("#");
                                    Console.Write(".");
                                }
                                Console.Write("#");//あまり１の分
                                Console.Write("\n");
                                for (int w = 0; w < (W / 2); w++)
                                {
                                    Console.Write(".");
                                    Console.Write("#");
                                }
                                Console.Write(".");//あまり１の分
                                Console.Write("\n");
                            }
                        }
                        if (W % 2 == 0)
                        {
                            for (int w = 0; w < (W / 2); w++)//あまり１の分
                            {
                                Console.Write("#");
                                Console.Write(".");
                            }
                            Console.Write("\n");
                        }
                        else
                        {
                            for (int w = 0; w < (W / 2); w++)//あまり１の分
                            {
                                Console.Write("#");
                                Console.Write(".");
                            }
                            Console.Write("#");//あまり１の分
                            Console.Write("\n");
                        }

                    }
                }
                Console.Write("\n");
            }
        }
    }
}



Measured memory_bytes: 15932