import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }
        sc.close();
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        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 i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        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 i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        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 i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        } true {
            int i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        } int i = 0; i 0 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 y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        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 {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            } {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            } int binary = i % 2; binary i % 2 i 2 i += 1 i 1 for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                } int x = 0; int x = 0; x 0 x < W x W x++ x++ x {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                } {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                } if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    } x % 2 == binary x % 2 x 2 binary {
                        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 i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        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 i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }
        sc.close();
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int i = 0;
            int H = sc.nextInt();
            int W = sc.nextInt();
            if (H == 0 && W == 0)
                break;
            for (int y = 0; y < H; y++) {
                int binary = i % 2;
                    i += 1;
                for (int x = 0; x < W; x++) {
                    if (x % 2 == binary) {
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }
        sc.close();
    }
}
