using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        int H = 0;
        int W = 0;
        List<int> Hnum = new List<int>();
        List<int> Wnum = new List<int>();

        while (true)
        {
            HandW(ref H, ref W);

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

            Hnum.Add(H);
            Wnum.Add(W);
        }


        for (int i = 0; i <= Wnum.Count-1; i++)

        {
            for (int i1 = 0; i1 <= Hnum[i]; i1++)
            {
                if (i1 % 2 == 0)
                {
                    for (int i2 = 0; i2 <= Wnum[i]; i2++)
                    {
                        if (i2 % 2 == 0)
                            Console.Write("#");
                        else
                            Console.Write(".");
                    }
                }
                else
                {
                    for (int i2 = 0; i2 <= Wnum[i]; i2++)
                    {
                        if (i2 % 2 == 0)
                            Console.Write(".");
                        else
                            Console.Write("#");
                    }
                }

                Console.WriteLine();
            }

            Console.WriteLine();
        }


    }

    static void HandW(ref int x,ref int y)
    {
      
        string[] str = Console.ReadLine().Split(' ');
        x = int.Parse(str[0]);
        y = int.Parse(str[1]);
  
    }

   
}