import java.util.Scanner;

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

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

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

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

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

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

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

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int i i j; j while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

        } true {
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

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

                System.out.printf("\n");

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

                System.out.printf("\n");

            } {
                for(j = 0;j < W;j++){
                    if(i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1){
                        System.out.printf("#");
                    }else{
                        System.out.printf(".");
                    }
                }

                System.out.printf("\n");

            } for(j = 0;j < W;j++){
                    if(i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1){
                        System.out.printf("#");
                    }else{
                        System.out.printf(".");
                    }
                } j = 0; j = 0 j 0 j < W j W j++ j++ j {
                    if(i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1){
                        System.out.printf("#");
                    }else{
                        System.out.printf(".");
                    }
                } {
                    if(i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1){
                        System.out.printf("#");
                    }else{
                        System.out.printf(".");
                    }
                } if(i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1){
                        System.out.printf("#");
                    }else{
                        System.out.printf(".");
                    } i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1 i % 2 == 0 && j % 2 == 0 i % 2 == 0 i % 2 i 2 0 j % 2 == 0 j % 2 j 2 0 i % 2 == 1 && j % 2 == 1 i % 2 == 1 i % 2 i 2 1 j % 2 == 1 j % 2 j 2 1 {
                        System.out.printf("#");
                    } System.out.printf("#") System.out.printf System.out System System.out "#" {
                        System.out.printf(".");
                    } System.out.printf(".") System.out.printf 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" String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

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

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

        }
    }
} Main
import java.util.Scanner;

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

        int i ,j;

        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();

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

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

                System.out.printf("\n");

            }

            System.out.printf("\n");

        }
    }
}
