import java.io.*;
import java.util.*;

class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while(true){
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        }
    }
} import java.io.*; io.* java import java.util.*; util.* java class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while(true){
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        }
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while(true){
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        }
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while(true){
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        }
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while(true){
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        } true {
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        } StringTokenizer st=new StringTokenizer(br.readLine()); st new StringTokenizer(br.readLine()) int h=Integer.parseInt(st.nextToken()); h Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int w=Integer.parseInt(st.nextToken()); w Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st boolean h_bool=false; h_bool false boolean w_bool=!h_bool; w_bool !h_bool h_bool if(w==0&&h==0) break; w==0&&h==0 w==0 w 0 h==0 h 0 break; for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            } int i=0; int i=0; i 0 i<h i h i++ i++ i {
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            } {
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            } h_bool=!h_bool h_bool !h_bool h_bool w_bool=!h_bool w_bool !h_bool h_bool for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                } int j=0; int j=0; j 0 j<w j w j++ j++ j {
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                } {
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                } w_bool=!w_bool w_bool !w_bool w_bool if(w_bool) System.out.print("#");
                    else System.out.print("."); w_bool System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out String[] args args
import java.io.*;
import java.util.*;

class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while(true){
            StringTokenizer st=new StringTokenizer(br.readLine());
            int h=Integer.parseInt(st.nextToken());
            int w=Integer.parseInt(st.nextToken());
            boolean h_bool=false;
            boolean w_bool=!h_bool;
            if(w==0&&h==0) break;
            for(int i=0;i<h;i++){
                h_bool=!h_bool;
                w_bool=!h_bool;
                for(int j=0;j<w;j++){
                    w_bool=!w_bool;
                    if(w_bool) System.out.print("#");
                    else System.out.print(".");
                }System.out.println();
            }System.out.println();
        }
    }
}