import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	}

	static void printChessboard(int H, int W) {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	}

	static void printChessboard(int H, int W) {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	} main {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int H; H int W; W while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		} true {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		} H = sc.nextInt() H sc.nextInt() sc.nextInt sc 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; printChessboard(H, W) printChessboard H W String[] args args static void printChessboard(int H, int W) {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	} printChessboard {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	} 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(".");

				if (j == (W - 1))
					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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		} {
			for (int j = 0; j < W; j++) {
				if((i+j)%2==0)
				System.out.print("#");
				
				else
					System.out.print(".");

				if (j == (W - 1))
					System.out.println("");
			}
		} for (int j = 0; j < W; j++) {
				if((i+j)%2==0)
				System.out.print("#");
				
				else
					System.out.print(".");

				if (j == (W - 1))
					System.out.println("");
			} 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 (j == (W - 1))
					System.out.println("");
			} {
				if((i+j)%2==0)
				System.out.print("#");
				
				else
					System.out.print(".");

				if (j == (W - 1))
					System.out.println("");
			} 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 System System.out "#" System.out.print(".") System.out.print System.out System System.out "." if (j == (W - 1))
					System.out.println(""); j == (W - 1) j (W - 1) W 1 System.out.println("") System.out.println System.out System System.out "" System.out.println() System.out.println System.out System System.out int H H int W W public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	}

	static void printChessboard(int H, int W) {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	}

	static void printChessboard(int H, int W) {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int H;
		int W;

		while (true) {
			H = sc.nextInt();
			W = sc.nextInt();

			if (H == 0 && W == 0)
				break;

			printChessboard(H, W);

		}

	}

	static void printChessboard(int H, int W) {
		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(".");

				if (j == (W - 1))
					System.out.println("");
			}
		}
		System.out.println();
	}

}