import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    }

}
 import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    }

} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    } main {
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        } true {

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        } int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc if(H == 0 && W == 0){
                break;
            }

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            } H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
                break;
            } break; {
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            } int i i j; j for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                } i=1; i=1 i 1 i<=H i H i++ i++ i {
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                } {
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                } for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    } j=1; j=1 j 1 j<=W j W j++ j++ j {
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    } {
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    } if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        } i % 2 == j % 2 i % 2 i 2 j % 2 j 2 {
                            System.out.print("#");
                        } System.out.print("#") System.out.print System.out System System.out "#" {
                            System.out.print(".");
                        } 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 sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    }

} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    }

} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        while(true){

            int H = sc.nextInt();
            int W = sc.nextInt();

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

            else{
                int i, j;

                for(i=1;i<=H;i++){
                    for(j=1;j<=W;j++){
                        if(i % 2 == j % 2){
                            System.out.print("#");
                        }
                        else{
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }      
        }

        sc.close();

    }

}

