import java.util.Scanner;

public class Main {

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

	}

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

	} main {
		Scanner sc = new Scanner(System.in);
		int h=0, w=0;
		while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if (H == 0 && W == 0){
				break;
			}
			for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int h=0 h 0 w=0; w 0 while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if (H == 0 && W == 0){
				break;
			}
			for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} true {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if (H == 0 && W == 0){
				break;
			}
			for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc if (H == 0 && W == 0){
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} h = 0; h = 0 h 0 h < H h H h++ h++ h {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				} w = 0; w = 0 w 0 w < W w W w++ w++ w {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				} {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				} if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					} h % 2 == 0 h % 2 h 2 0 {
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						} w % 2 == 0 w % 2 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 "." {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					} if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						} w % 2 == 0 w % 2 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 sc = new Scanner(System.in);
		int h=0, w=0;
		while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if (H == 0 && W == 0){
				break;
			}
			for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (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 sc = new Scanner(System.in);
		int h=0, w=0;
		while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if (H == 0 && W == 0){
				break;
			}
			for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (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 sc = new Scanner(System.in);
		int h=0, w=0;
		while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if (H == 0 && W == 0){
				break;
			}
			for (h = 0; h < H; h++) {
				for (w = 0; w < W; w++) {
					if (h % 2 == 0){
						if (w % 2 == 0){
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (w % 2 == 0){
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}

	}

}