import java.util.Scanner;

class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        }
        scan.close();
    }

    public static void writeRectangle(int height, int width) {
        for (int i = 0; i < height; i++){
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        }
        System.out.println();
    }

} import java.util.Scanner; Scanner java.util class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        }
        scan.close();
    }

    public static void writeRectangle(int height, int width) {
        for (int i = 0; i < height; i++){
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        }
        System.out.println();
    }

} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        }
        scan.close();
    } main {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        }
        scan.close();
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while (true) {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        } true {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        } int height = scan.nextInt(); height scan.nextInt() scan.nextInt scan int width  = scan.nextInt(); width scan.nextInt() scan.nextInt scan if (height == 0 && width == 0) {
                break;
            } height == 0 && width == 0 height == 0 height 0 width == 0 width 0 {
                break;
            } break; writeRectangle(height, width) writeRectangle height width scan.close() scan.close scan String[] args args public static void writeRectangle(int height, int width) {
        for (int i = 0; i < height; i++){
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        }
        System.out.println();
    } writeRectangle {
        for (int i = 0; i < height; i++){
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        }
        System.out.println();
    } for (int i = 0; i < height; i++){
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        } int i = 0; int i = 0; i 0 i < height i height i++ i++ i {
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        } {
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        } switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            } i % 2 i 2 case 0: 0 case 0: for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                } int j = 0; int j = 0; j 0 j < width j width j++ j++ j {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                } {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                } switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    } j % 2 j 2 case 0: 0 case 0: System.out.print("#") System.out.print System.out System System.out "#" break; case 1: 1 case 1: System.out.print(".") System.out.print System.out System System.out "." break; break; case 1: 1 case 1: for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                } int j = 0; int j = 0; j 0 j < width j width j++ j++ j {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                } {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                } switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    } j % 2 j 2 case 0: 0 case 0: System.out.print(".") System.out.print System.out System System.out "." break; case 1: 1 case 1: System.out.print("#") System.out.print System.out System System.out "#" break; break; System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out int height height int width width
import java.util.Scanner;

class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int height = scan.nextInt();
            int width  = scan.nextInt();

            if (height == 0 && width == 0) {
                break;
            }

            writeRectangle(height, width);
        }
        scan.close();
    }

    public static void writeRectangle(int height, int width) {
        for (int i = 0; i < height; i++){
            switch (i % 2) {
            case 0:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print("#");
                        break;

                    case 1:
                        System.out.print(".");
                        break;
                    }
                }
                break;

            case 1:
                for (int j = 0; j < width; j++) {
                    switch (j % 2) {
                    case 0:
                        System.out.print(".");
                        break;

                    case 1:
                        System.out.print("#");
                        break;
                    }
                }
                break;
            }
            System.out.println();
        }
        System.out.println();
    }

}