import java.util.Scanner;

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

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

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

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

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

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        } true {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        } int h = sc.nextInt(); h sc.nextInt() sc.nextInt sc int 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; for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            } int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            } {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            } for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                } int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                } {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                } boolean oddRow = (i % 2) == 1; oddRow (i % 2) == 1 (i % 2) i 2 1 boolean oddColumn = (j % 2) == 1; oddColumn (j % 2) == 1 (j % 2) j 2 1 if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    } (oddRow && oddColumn) || (!oddRow && !oddColumn) (oddRow && oddColumn) oddRow oddColumn (!oddRow && !oddColumn) !oddRow oddRow !oddColumn oddColumn {
                        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 "" sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

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

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

        sc.close();
    }
} Main
import java.util.Scanner;

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

        while (true) {
            int h = sc.nextInt();
            int w = sc.nextInt();

            if (h == 0 && w == 0) break;

            for (int i = 0; i < h; i++) {
                for (int j = 0; j < w; j++) {
                    boolean oddRow = (i % 2) == 1;
                    boolean oddColumn = (j % 2) == 1;

                    if ((oddRow && oddColumn) || (!oddRow && !oddColumn)) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }

                }
                System.out.println("");
            }
            System.out.println("");
        }

        sc.close();
    }
}
