import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	}
} Main public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	} main {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

					} else if (((i + 1) % 2 == 0) && ((j + 1) % 2 != 0)) {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} true {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

					} else if (((i + 1) % 2 == 0) && ((j + 1) % 2 != 0)) {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} String[] str = (br.readLine()).split(" "); str (br.readLine()).split(" ") (br.readLine()).split (br.readLine()) br.readLine br " " int H = 0; H 0 int W = 0; W 0 H = Integer.parseInt(str[0]) H Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 W = Integer.parseInt(str[1]) W Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 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 + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

					} else if (((i + 1) % 2 == 0) && ((j + 1) % 2 != 0)) {
						System.out.print(".");
					}
				} int j = 0; int j = 0; j 0 j < W j W j++ j++ j {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

					} else if (((i + 1) % 2 == 0) && ((j + 1) % 2 != 0)) {
						System.out.print(".");
					}
				} {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

					} System.out.print("#") System.out.print System.out System System.out "#" if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

					} else if (((i + 1) % 2 == 0) && ((j + 1) % 2 != 0)) {
						System.out.print(".");
					} ((i + 1) % 2 != 0) && ((j + 1) % 2 == 0) ((i + 1) % 2 != 0) (i + 1) % 2 (i + 1) i 1 2 0 ((j + 1) % 2 == 0) (j + 1) % 2 (j + 1) j 1 2 0 {
						System.out.print(".");

					} System.out.print(".") System.out.print System.out System System.out "." if (((i + 1) % 2 == 0) && ((j + 1) % 2 != 0)) {
						System.out.print(".");
					} ((i + 1) % 2 == 0) && ((j + 1) % 2 != 0) ((i + 1) % 2 == 0) (i + 1) % 2 (i + 1) i 1 2 0 ((j + 1) % 2 != 0) (j + 1) % 2 (j + 1) j 1 2 0 {
						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) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	}
} public class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			String[] str = (br.readLine()).split(" ");

			int H = 0;
			int W = 0;

			H = Integer.parseInt(str[0]);
			W = Integer.parseInt(str[1]);

			if (H == 0 && W == 0) {
				break;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {

					if (((i + 1) % 2 != 0) && ((j + 1) % 2 != 0)) {
						System.out.print("#");

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

					} else if (((i + 1) % 2 != 0) && ((j + 1) % 2 == 0)) {
						System.out.print(".");

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

	}
}