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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    }
} 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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    }
} 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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0) {break;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    } 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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        } true {
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0) {break;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

                }else if(i%2==0){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print(".");
                        }else if(j%2==0){
                            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;} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {break;} break; if (W > 300 || H < 1){break;} W > 300 || H < 1 W > 300 W 300 H < 1 H 1 {break;} break; for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

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

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

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

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

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

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

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

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

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

                } for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print(".");
                        }else if(j%2==0){
                            System.out.print("#");
                        }
                    } int j=1; int j=1; j 1 j<=W j W j++ j++ j {
                        if(j%2==1){
                            System.out.print(".");
                        }else if(j%2==0){
                            System.out.print("#");
                        }
                    } {
                        if(j%2==1){
                            System.out.print(".");
                        }else if(j%2==0){
                            System.out.print("#");
                        }
                    } if(j%2==1){
                            System.out.print(".");
                        }else if(j%2==0){
                            System.out.print("#");
                        } j%2==1 j%2 j 2 1 {
                            System.out.print(".");
                        } System.out.print(".") System.out.print System.out System System.out "." if(j%2==0){
                            System.out.print("#");
                        } j%2==0 j%2 j 2 0 {
                            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 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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    }
} 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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    }
} 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;}
            if (W > 300 || H < 1){break;}
            for(int i=1;i<=H;i++){
                if(i%2==1){
                    for(int j=1;j<=W;j++){
                        if(j%2==1){
                            System.out.print("#");
                        }else if(j%2==0){
                            System.out.print(".");
                        }
                    }
                    System.out.println();

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

                }
            }
            System.out.println();
        }
    }
}
