import java.util.Scanner;

public class Main {
	private static Scanner sc;

	public static void main(String[] args) {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}

	private static void display(int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 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 {
	private static Scanner sc;

	public static void main(String[] args) {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}

	private static void display(int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		}
		System.out.println();
	}
} Main private static Scanner sc; sc public static void main(String[] args) {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	} main {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	} sc = new Scanner(System.in) sc new Scanner(System.in) int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		} H != 0 && W != 0 H != 0 H 0 W != 0 W 0 {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		} display(H, W) display H W H = sc.nextInt() H sc.nextInt() sc.nextInt sc W = sc.nextInt() W sc.nextInt() sc.nextInt sc String[] args args private static void display(int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		}
		System.out.println();
	} display {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		}
		System.out.println();
	} for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		} int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		} {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		} for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			} int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			} {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			} if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				} (i + 1) % 2 == 0 (i + 1) % 2 (i + 1) i 1 2 0 {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					} (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 "." {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				} if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					} (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 int h h int w w public class Main {
	private static Scanner sc;

	public static void main(String[] args) {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}

	private static void display(int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		}
		System.out.println();
	}
} public class Main {
	private static Scanner sc;

	public static void main(String[] args) {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}

	private static void display(int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		}
		System.out.println();
	}
} Main
import java.util.Scanner;

public class Main {
	private static Scanner sc;

	public static void main(String[] args) {
		sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while (H != 0 && W != 0) {
			display(H, W);
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}

	private static void display(int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if ((i + 1) % 2 == 0) {
					if ((j + 1) % 2 == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}					
				} else {
					if ((j + 1) % 2 == 0) {
						System.out.print(".");
					} else {
						System.out.print("#");
					}
				}
			}
			System.out.println();
		}
		System.out.println();
	}
}