import java.util.*;

public class Main{
    public static void main(String[] args){
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    }
} Main public static void main(String[] args){
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    } main {
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    } int h h w; w int i i j j k = 0; k 0 String n = System.getProperty("line.separator"); n System.getProperty("line.separator") System.getProperty System "line.separator" Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) String nu; nu while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        } true {
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        } nu = scanner.next() nu scanner.next() scanner.next scanner h = Integer.parseInt(nu) h Integer.parseInt(nu) Integer.parseInt Integer nu nu = scanner.next() nu scanner.next() scanner.next scanner w = Integer.parseInt(nu) w Integer.parseInt(nu) Integer.parseInt Integer nu if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

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

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

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

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

                } for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    } j = 0; j = 0 j 0 j < w j w j++ j++ j {
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    } {
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    } if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print("."); (j + i)% 2 == 0 (j + i)% 2 (j + i) j i 2 0 {
                            System.out.print("#");
                        } System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." System.out.print(n) System.out.print System.out System System.out n k = 0 k 0 System.out.print(n) System.out.print System.out System System.out n scanner.close() scanner.close scanner String[] args args public class Main{
    public static void main(String[] args){
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    }
} public class Main{
    public static void main(String[] args){
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    }
} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
        int h, w;
        int i, j, k = 0;
        String n = System.getProperty("line.separator");
        Scanner scanner = new Scanner(System.in);
        String nu;
        while(true){
            nu = scanner.next();
            h = Integer.parseInt(nu);
            nu = scanner.next();
            w = Integer.parseInt(nu);
            if(h == 0 && w == 0) break;
            else{
                for(i = 0; i < h; i++){
                    for(j = 0; j < w; j++){
                        if((j + i)% 2 == 0){
                            System.out.print("#");
                        }
                        else System.out.print(".");
                    }
                    System.out.print(n);

                }
            }
            k = 0;
            System.out.print(n);
        }
        scanner.close();
    }
}
