import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    }
} Main public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    } main {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    } try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        } {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        } Scanner scanner = new Scanner(System.in) Scanner scanner = new Scanner(System.in) new Scanner(System.in) int a a b; b while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            } (a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0 (a = scanner.nextInt()) != 0 (a = scanner.nextInt()) a scanner.nextInt() scanner.nextInt scanner 0 (b = scanner.nextInt()) != 0 (b = scanner.nextInt()) b scanner.nextInt() scanner.nextInt scanner 0 {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            } for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                } int i = 0; int i = 0; i 0 i < a i a i++ i++ i {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                } {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                } for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    } int j = 0; int j = 0; j 0 j < b j b j++ j++ j {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    } {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    } if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        } (i % 2 == j % 2) i % 2 i 2 j % 2 j 2 {
                            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.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out String[] args args public class Main {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    }
} public class Main {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
        }
    }
}