import java.util.Scanner;

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

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        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) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }

    }

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

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }

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

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }

    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        } true {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        } int H = scan.nextInt() H scan.nextInt() scan.nextInt scan W = scan.nextInt(); W scan.nextInt() scan.nextInt scan if (H == 0 && W == 0) break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            } int i = 1; int i = 1; i 1 i <= H i H i++ i++ i {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            } {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            } for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                } int j = 1; int j = 1; j 1 j <= W j W j++ j++ j {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                } {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                } if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    } (i + j) % 2 == 0 (i + j) % 2 (i + j) i j 2 0 {
                        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) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }

    }

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

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        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) {
        Scanner scan = new Scanner(System.in);

        while (true) {
            int H = scan.nextInt(), W = scan.nextInt();
            if (H == 0 && W == 0) break;

            for (int i = 1; i <= H; i++) {
                for (int j = 1; j <= W; j++) {
                    if ((i + j) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }

    }

}