import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				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);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	} main {
		Scanner sc = new Scanner(System.in);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} true {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		} int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc if (a == 0 && b == 0)
				break; a == 0 && b == 0 a == 0 a 0 b == 0 b 0 break; for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			} int i = 0; int i = 0; i 0 i < a i a i++ i++ i {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			} {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			} for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				} int c = 0; int c = 0; c 0 c < b c b c++ c++ c {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				} {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				} if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					} (i + c) % 2 == 0 (i + c) % 2 (i + c) i c 2 0 {
						System.out.printf("#");
					} System.out.printf("#") System.out.printf System.out System System.out "#" {
						System.out.printf(".");
					} System.out.printf(".") System.out.printf 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);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				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);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0)
				break;
			for (int i = 0; i < a; i++) {
				for (int c = 0; c < b; c++) {
					if ((i + c) % 2 == 0) {
						System.out.printf("#");
					} else {
						System.out.printf(".");
					}
				}
				System.out.println();
			}
			System.out.println();
		}
	}
}
