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

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\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);
        int h,w;

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }

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

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int h,w;

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int h h w; w while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        } true {
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        } h=sc.nextInt() h sc.nextInt() sc.nextInt sc 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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        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 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            } {
                for(int j=0; j<w; j++){
                    if((i%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            } for(int j=0; j<w; j++){
                    if((i%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        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 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                } {
                    if((i%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                } if((i%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    } (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.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" sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int h,w;

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }

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

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }

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

        while(true){
            h=sc.nextInt();
            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%2==0 && j%2==0) || (i%2==1 && j%2==1)){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }

        sc.close();
    }
}

