import java.util.Scanner;

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

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