using System;

class Rectangle
{
    public static void Main()
    {
        while (true)
        {
            string[] s = Console.ReadLine().Split();

            int H = int.Parse(s[0]);
            int W = int.Parse(s[1]);

            if (H == 0 && W == 0)
            {
                break;
            }

            for (int i = 0; i < H; i++)
            {
                if (H == 1 && W == 1)
                {
                    Console.Write("#");
                }
                else if (i % 2 == 0)
                {
                    for (int k = 0; k < W / 2; k += 2)
                    {
                        Console.Write("#.");
                    }
                    if (W % 2 == 1)
                    {
                        Console.Write("#");
                    }
                }
                else
                {
                    for (int k = 0; k < W / 2; k += 2)
                    {
                        Console.Write(".#");
                    }
                    if (W % 2 == 1)
                    {
                        Console.Write(".");
                    }
                }
                Console.WriteLine();
            }
            Console.WriteLine();
        }
    }
}
