import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	} main {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) StringBuilder text = new StringBuilder(); text new StringBuilder() while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		} true {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		} 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) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} scan.close() scan.close scan text.deleteCharAt(text.lastIndexOf("\n")) text.deleteCharAt text text.lastIndexOf("\n") text.lastIndexOf text "\n" System.out.println(text.toString()) System.out.println System.out System System.out text.toString() text.toString text break; {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			} boolean nextChar = true; nextChar true for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				} int i = 0; int i = 0; i 0 i < H i H i++ i++ i {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				} {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				} if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false; i % 2 == 0 i % 2 i 2 0 nextChar = true nextChar true nextChar = false nextChar false for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					} int t = 0; int t = 0; t 0 t < W t W t++ t++ t {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					} {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					} if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						} nextChar {
							text.append("#");
							nextChar = false;
						} text.append("#") text.append text "#" nextChar = false nextChar false {
							text.append(".");
							nextChar = true;
						} text.append(".") text.append text "." nextChar = true nextChar true text.append("\n") text.append text "\n" text.append("\n") text.append text "\n" String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder text = new StringBuilder();
		while (true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if (H == 0 && W == 0) {
				scan.close();
				text.deleteCharAt(text.lastIndexOf("\n"));
				System.out.println(text.toString());
				break;
			} else {
				boolean nextChar = true;
				for (int i = 0; i < H; i++) {
					if(i % 2 == 0)
						nextChar = true;
					else
						nextChar = false;
					for (int t = 0; t < W; t++) {
						if (nextChar) {
							text.append("#");
							nextChar = false;
						} else {
							text.append(".");
							nextChar = true;
						}
					}
					text.append("\n");
				}
				text.append("\n");
			}
		}
	}
}