import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	} main {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int H; H int W; W for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} int i = 0; int i = 0; i 0 i < 10000 i 10000 i ++ i ++ i {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} H = scan.nextInt() H scan.nextInt() scan.nextInt scan W = scan.nextInt() W scan.nextInt() scan.nextInt scan if (H == 0 && W == 0) {
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			} int h = 0; int h = 0; h 0 h < H h H h++ h++ h {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			} {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			} for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				} int w = 0; int w = 0; w 0 w < W w W w++ w++ w {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				} {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				} if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					} (h + w) % 2 == 0 (h + w) % 2 (h + w) h w 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) {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int H;
		int W;
		for (int i = 0; i < 10000; i ++) {
			H = scan.nextInt();
			W = scan.nextInt();
			if (H == 0 && W == 0) {
				break;
			}
			for (int h = 0; h < H; h++) {
				for (int w = 0; w < W; w++) {
					if ((h + w) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}

}