import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int H, W;
		boolean sharp = false;

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

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		}
	}
} import java.util.Scanner; Scanner java.util class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int H, W;
		boolean sharp = false;

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

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		}
	}
} Main public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int H, W;
		boolean sharp = false;

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

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		}
	} main {
		Scanner scanner = new Scanner(System.in);
		int H, W;
		boolean sharp = false;

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

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int H H W; W boolean sharp = false; sharp false while (true) {
			H = scanner.nextInt();
			W = scanner.nextInt();

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		} true {
			H = scanner.nextInt();
			W = scanner.nextInt();

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		} H = scanner.nextInt() H scanner.nextInt() scanner.nextInt scanner 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 i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			} int i = 0; int i = 0; i 0 i < H i H i++ i++ i {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			} {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			} if (i % 2 == 0)
					sharp = false;
				else
					sharp = true; i % 2 == 0 i % 2 i 2 0 sharp = false sharp false sharp = true sharp true for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				} int i2 = 0; int i2 = 0; i2 0 i2 < W i2 W i2++ i2++ i2 {
					System.out.print((sharp = !sharp) ? "#" : ".");
				} {
					System.out.print((sharp = !sharp) ? "#" : ".");
				} System.out.print((sharp = !sharp) ? "#" : ".") System.out.print System.out System System.out (sharp = !sharp) ? "#" : "." (sharp = !sharp) sharp !sharp sharp "#" "." 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
import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int H, W;
		boolean sharp = false;

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

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

			for (int i = 0; i < H; i++) {
				if (i % 2 == 0)
					sharp = false;
				else
					sharp = true;

				for (int i2 = 0; i2 < W; i2++) {
					System.out.print((sharp = !sharp) ? "#" : ".");
				}

				System.out.println();
			}

			System.out.println();
		}
	}
}