using System;
using System.Collections.Generic;
using System.Linq;
namespace ITP1_5_C
{
    class Problem
    {

        public static List<string[]> getinputdata (){

            List<string[]> list_temp = new List<string[]>();
            string strdata = Console.ReadLine ();

            while (strdata!=null) {

                string[] s_temp = strdata.Split (' ');

                list_temp.Add (s_temp);

                strdata = Console.ReadLine ();

            }
            return list_temp;
        }

        public static void DrarChess (int h,int w,ref bool flg){


            
            //????±?????????°??????????????????
            for (int j = 0; j < h; j++)
            {

                //?\???°????????´???(#????????????)
                if(flg){

                    if (w % 2 == 0)
                    {
                        string s= string.Concat(Enumerable.Repeat("#." ,w/2));
                        Console.WriteLine(s);

                    }
                    else
                    {
                        string s= string.Concat(Enumerable.Repeat("#." ,w/2));
                        s+="#";
                        Console.WriteLine(s);

                    }

                    flg=false;
                }else{

                    if (w % 2 == 0)
                    {
                        string s = string.Concat(Enumerable.Repeat(".#" ,w/2));
                        Console.WriteLine(s);

                    }
                    else
                    {
                        string s= string.Concat(Enumerable.Repeat(".#" ,w/2));
                        s+=".";

                        Console.WriteLine(s);

                    }

                    flg=true;
                }


            }

            Console.WriteLine();
        }

        public static void Main (string[] args)
        {
            List<string[]> list_result = new List<string[]>();
            list_result = getinputdata ();

            int H;
            int W;

            //????±????rec??°????????????
            for (int i = 0; i < list_result.Count-1; i++)
            {

                bool flg = true;
                H = int.Parse(list_result[i][0]);
                W = int.Parse(list_result[i][1]);

                DrarChess(H, W,ref flg);
            }
          
        }
    }
}