import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 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 scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            }
            System.out.println("");
        }
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            }
            System.out.println("");
        }
    } main {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            }
            System.out.println("");
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            }
            System.out.println("");
        } scanner.hasNextInt() scanner.hasNextInt scanner {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            }
            System.out.println("");
        } int h = scanner.nextInt(); h scanner.nextInt() scanner.nextInt scanner int w = scanner.nextInt(); w scanner.nextInt() scanner.nextInt scanner if (w == 0 && h == 0) {
                break;
            } w == 0 && h == 0 w == 0 w 0 h == 0 h 0 {
                break;
            } break; for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            } int y = 0; int y = 0; y 0 y < h y h y++ y++ y {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            } {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            } for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                } int x = 0; int x = 0; x 0 x < w x w x++ x++ x {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                } {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                } if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    } (x + y) % 2 == 0 (x + y) % 2 (x + y) x y 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 scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 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 scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 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 scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int h = scanner.nextInt();
            int w = scanner.nextInt();
            if (w == 0 && h == 0) {
                break;
            }
            for (int y = 0; y < h; y++) {
                for (int x = 0; x < w; x++) {
                    if ((x + y) % 2 == 0) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.println("");
            }
            System.out.println("");
        }
    }
}

