import java.util.Scanner;

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

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		}
		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

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

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		}
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		}
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		} true {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		} int height = sc.nextInt(); height sc.nextInt() sc.nextInt sc int width = sc.nextInt(); width sc.nextInt() sc.nextInt sc if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			} height == 0 && width == 0 height == 0 height 0 width == 0 width 0 {
				break;
			} break; {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			} for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				} int i = 0; int i = 0; i 0 i < height i height i++ i++ i {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				} {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				} for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					} int j = 0; int j = 0; j 0 j < width j width 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 {
							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 {
							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 {
							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 {
							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 {
							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.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 sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

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

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		}
		sc.close();
	}
} Main
import java.util.Scanner;

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

		while (true) {
			int height = sc.nextInt();
			int width = sc.nextInt();

			if(height == 0 && width == 0) {
				break;
			} else {

				for(int i = 0;i < height;i++) {
					for(int j = 0;j < width;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 {
							System.out.print("#");
						}
					}
					System.out.println();
				}
				System.out.println();

			}

		}
		sc.close();
	}
}