using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;

public class Program
{

	public void Proc()
	{
        System.Text.StringBuilder ans = new System.Text.StringBuilder();
        while(true) {
            string inpt = Reader.ReadLine();
            if(inpt == null) {
                break;
            }
            int[] size = inpt.Split(' ').Select(a => int.Parse(a)).ToArray();
            if(size.Count(a=>a<1)>=2) {
                break;
            }
            ans.AppendLine(GetAns(size[0], size[1]));
        }

        Console.Write(ans.ToString());
    
    }

    private string GetAns(int h, int w) {
        System.Text.StringBuilder tmp = new System.Text.StringBuilder();
        for (int i = 0; i < w - 1; i++) {
            if(i%2==0) {
				tmp.Append(".");
			} else {
				tmp.Append("#");
            }
        }
        string baseText = tmp.ToString();
        tmp = new System.Text.StringBuilder();
        for (int i = 0; i < h; i++) {
			if (i % 2 == 0)
			{
				tmp.AppendLine("#" + baseText);
			}
			else
			{
				tmp.AppendLine(baseText + "#");
			}
		}
        return tmp.ToString();
    }


    public class Reader
	{
		private static StringReader sr;
		public static bool IsDebug = false;
		public static string ReadLine()
		{
			if (IsDebug)
			{
				if (sr == null)
				{
					sr = new StringReader(InputText.Trim());
				}
				return sr.ReadLine();
			}
			else
			{
				return Console.ReadLine();
			}
		}
		private static string InputText = @"



3 4
5 6
3 3
2 2
1 1
0 0



";
	}

	public static void Main(string[] args)
	{
#if DEBUG
		Reader.IsDebug = true;
#endif
		Program prg = new Program();
		prg.Proc();
	}
}