import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		int H,W;
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			H=scan.nextInt();
			W=scan.nextInt();
			if(H == 0 && W== 0) {
				break;
			}

			for(int i = 0; i < H; i++) {
				for(int j = 0; 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) {
		int H,W;
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			H=scan.nextInt();
			W=scan.nextInt();
			if(H == 0 && W== 0) {
				break;
			}

			for(int i = 0; i < H; i++) {
				for(int j = 0; 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) {
		int H,W;
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			H=scan.nextInt();
			W=scan.nextInt();
			if(H == 0 && W== 0) {
				break;
			}

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

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

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

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

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

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

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

				}
				System.out.println("");
			}
			System.out.println("");
		} scan.hasNext() scan.hasNext scan {
			H=scan.nextInt();
			W=scan.nextInt();
			if(H == 0 && W== 0) {
				break;
			}

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

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

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

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

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

			for(int i = 0; i < H; i++) {
				for(int j = 0; 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) {
		int H,W;
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			H=scan.nextInt();
			W=scan.nextInt();
			if(H == 0 && W== 0) {
				break;
			}

			for(int i = 0; i < H; i++) {
				for(int j = 0; 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) {
		int H,W;
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			H=scan.nextInt();
			W=scan.nextInt();
			if(H == 0 && W== 0) {
				break;
			}

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

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

	}
}