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[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				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[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				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[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} main {

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

		while(true) {
			String[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while(true) {
			String[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} true {
			String[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

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

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

		while(true) {
			String[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				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[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				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[] strArray = br.readLine().split(" ");
			int H = Integer.parseInt(strArray[0]);
			int W = Integer.parseInt(strArray[1]);

			if (H ==0 && W == 0) {
				break;
			}
			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(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
}