import java.util.Scanner;

class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(true){
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }
    }
} import java.util.Scanner; Scanner java.util class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(true){
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }
    }
} Main public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(true){
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }
    } main {
        Scanner in = new Scanner(System.in);
        while(true){
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) while(true){
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        } true {
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        } int h = in.nextInt(); h in.nextInt() in.nextInt in int w = in.nextInt(); w in.nextInt() in.nextInt in 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%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\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%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            } {
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            } for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(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%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                } {
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                } if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    } i%2 != 0 i%2 i 2 0 {
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    } if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            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.print(".");
                        } System.out.print(".") System.out.print System.out System System.out "." {
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    } if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            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.print("#");
                        } System.out.print("#") System.out.print System.out System System.out "#" System.out.print("\n") System.out.print System.out System System.out "\n" System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args
import java.util.Scanner;

class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(true){
            int h = in.nextInt();
            int w = in.nextInt();
            if(h == 0 && w == 0){
                break;
            }
            for(int i=0; i<h; i++){
                for(int j=0; j<w; j++){
                    if(i%2 != 0 ){
                        if(j%2 !=0) {
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 !=0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                        }
                    }

                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }
    }
}