public class Main {
	public static void main(String[] args){
		java.util.Scanner scan = new java.util.Scanner(System.in);
		while(true){
			int H = scan.nextInt();
			int 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 % 2 == 0) && (i != 0) && (j % 2 == 0) && (j != 0)) || (i % 2 != 0) && (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){
		java.util.Scanner scan = new java.util.Scanner(System.in);
		while(true){
			int H = scan.nextInt();
			int 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 % 2 == 0) && (i != 0) && (j % 2 == 0) && (j != 0)) || (i % 2 != 0) && (j % 2 != 0)){
						System.out.print("#");
					}else{
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}

	}

} Main public static void main(String[] args){
		java.util.Scanner scan = new java.util.Scanner(System.in);
		while(true){
			int H = scan.nextInt();
			int 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 % 2 == 0) && (i != 0) && (j % 2 == 0) && (j != 0)) || (i % 2 != 0) && (j % 2 != 0)){
						System.out.print("#");
					}else{
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}

	} main {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		while(true){
			int H = scan.nextInt();
			int 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 % 2 == 0) && (i != 0) && (j % 2 == 0) && (j != 0)) || (i % 2 != 0) && (j % 2 != 0)){
						System.out.print("#");
					}else{
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}

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

	}

} Main
public class Main {
	public static void main(String[] args){
		java.util.Scanner scan = new java.util.Scanner(System.in);
		while(true){
			int H = scan.nextInt();
			int 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 % 2 == 0) && (i != 0) && (j % 2 == 0) && (j != 0)) || (i % 2 != 0) && (j % 2 != 0)){
						System.out.print("#");
					}else{
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}

	}

}