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

public class Main {
	static int height = 0;
	static int weight = 0;

	public static void main(String[] args) throws Exception {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
	static int height = 0;
	static int weight = 0;

	public static void main(String[] args) throws Exception {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	}
} Main static int height = 0; height 0 static int weight = 0; weight 0 public static void main(String[] args) throws Exception {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	} main {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	} boolean zeroFlag = true; zeroFlag true BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String line = br.readLine(); line br.readLine() br.readLine br while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		} zeroFlag {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		} String[] nyuryokuStr = line.split("[\\s]+"); nyuryokuStr line.split("[\\s]+") line.split line "[\\s]+" height = Integer.parseInt(nyuryokuStr[0]) height Integer.parseInt(nyuryokuStr[0]) Integer.parseInt Integer nyuryokuStr[0] nyuryokuStr 0 weight = Integer.parseInt(nyuryokuStr[1]) weight Integer.parseInt(nyuryokuStr[1]) Integer.parseInt Integer nyuryokuStr[1] nyuryokuStr 1 if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			} height == 0 && weight == 0 height == 0 height 0 weight == 0 weight 0 {
				zeroFlag = false;
			} zeroFlag = false zeroFlag false {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			} for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				} int h = 0; int h = 0; h 0 h < height h height h++ h++ h {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				} {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				} for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} int w = 0; int w = 0; w 0 w < weight w weight w++ w++ w {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						} ((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1)) ((w % 2 == 0) && (h % 2 == 0)) (w % 2 == 0) w % 2 w 2 0 (h % 2 == 0) h % 2 h 2 0 ((w % 2 == 1) && (h % 2 == 1)) (w % 2 == 1) w % 2 w 2 1 (h % 2 == 1) h % 2 h 2 1 {
							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 line = br.readLine() line br.readLine() br.readLine br String[] args args public class Main {
	static int height = 0;
	static int weight = 0;

	public static void main(String[] args) throws Exception {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	}
} public class Main {
	static int height = 0;
	static int weight = 0;

	public static void main(String[] args) throws Exception {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	}
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	static int height = 0;
	static int weight = 0;

	public static void main(String[] args) throws Exception {
		boolean zeroFlag = true;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();

		while (zeroFlag) {
			String[] nyuryokuStr = line.split("[\\s]+");
			height = Integer.parseInt(nyuryokuStr[0]);
			weight = Integer.parseInt(nyuryokuStr[1]);
			if (height == 0 && weight == 0) {
				zeroFlag = false;
			} else {
				for (int h = 0; h < height; h++) {
					for (int w = 0; w < weight; w++) {
						if (((w % 2 == 0) && (h % 2 == 0))
								|| ((w % 2 == 1) && (h % 2 == 1))) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
					System.out.println();
				}
				System.out.println();
				line = br.readLine();
			}
		}
	}
}