import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner input = new Scanner(System.in);
        StringBuilder build = new StringBuilder();
        while(true){
            int h = input.nextInt();
            int w = input.nextInt();
            if(h==0&&w==0){
                break;
            }
            for(int n = 0; n < h; n++){
                for(int i = 0; i < w; i++){
                    if((n%2 == 1 && i%2 == 1) || (n%2 == 0 && i%2 == 0)){
                    build.append("#");
                    }else{
                    build.append(".");
                    }
                }
                build.append("\n");
            }
             build.append("\n");
        }
        System.out.print(build);
    }
} import java.util.Scanner; Scanner java.util public class Main {

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

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

    public static void main(String[] args) throws Exception {
        Scanner input = new Scanner(System.in);
        StringBuilder build = new StringBuilder();
        while(true){
            int h = input.nextInt();
            int w = input.nextInt();
            if(h==0&&w==0){
                break;
            }
            for(int n = 0; n < h; n++){
                for(int i = 0; i < w; i++){
                    if((n%2 == 1 && i%2 == 1) || (n%2 == 0 && i%2 == 0)){
                    build.append("#");
                    }else{
                    build.append(".");
                    }
                }
                build.append("\n");
            }
             build.append("\n");
        }
        System.out.print(build);
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner input = new Scanner(System.in);
        StringBuilder build = new StringBuilder();
        while(true){
            int h = input.nextInt();
            int w = input.nextInt();
            if(h==0&&w==0){
                break;
            }
            for(int n = 0; n < h; n++){
                for(int i = 0; i < w; i++){
                    if((n%2 == 1 && i%2 == 1) || (n%2 == 0 && i%2 == 0)){
                    build.append("#");
                    }else{
                    build.append(".");
                    }
                }
                build.append("\n");
            }
             build.append("\n");
        }
        System.out.print(build);
    }
}