using System;

class Program
{
    static void Main()
    {
            int i, j, x,count=0;
            int[] h = new int[2000];
            int[] w = new int[2000];
            for (i = 0; i < 2000; i++)
            {
                string inp = Console.ReadLine();
                string[] data = inp.Split();
                h[i] = int.Parse(data[0]);
                w[i] = int.Parse(data[1]);
                if (h[i] == 0 && w[i] == 0)
                {
                    break;
                }
            }
            for (x = 0; x < 2000; x++)
            {
                if (h[x] == 0 && w[x] == 0)
                {
                    break;
                }
                for (i = 0; i < h[x]; i++)
                {
                    for (j = 0; j < w[x]; j++)
                    {
                        if ((i+j) % 2 == 0)
                        {
                            Console.Write("#");
                        }else
                        {
                            Console.Write(".");
                        }
                    }
                    Console.Write("\n");
                }
                Console.Write("\n");
            }
    }
}
