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

}
