import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                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 (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        }
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        }
    } main {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        } true {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                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 (H == 0 && W == 0) break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            } int h = 0; int h = 0; h 0 h < H h H h++ h++ h {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            } {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            } char c = (h % 2 == 0 ? '#' : '.'); c (h % 2 == 0 ? '#' : '.') h % 2 == 0 h % 2 h 2 0 '#' '.' for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                } int w = 0; int w = 0; w 0 w < W w W w++ w++ w {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                } {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                } System.out.print(c) System.out.print System.out System System.out c c = (c == '.' ? '#' : '.') c (c == '.' ? '#' : '.') c == '.' c '.' '#' '.' 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 (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                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 (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        }
    }
}
