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

        }
    }
}