using System;

class Program
{
    static void Main()
    {
        while(true)
        {
            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;
                string odd="", even="";
                for(int i=0;i<W;i++)
                {
                    odd += i % 2 == 0 ? "#" : ".";
                    even += i % 2 == 0 ? "." : "#";
                }
                for(int i =1;i<=H;i++)
                {
                    Console.WriteLine(i%2==0 ? even:odd);
                }
                Console.WriteLine("");
            }

        }
    }
}