
import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							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);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							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);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println();

			}
			System.out.println();

		}

	} main {
		Scanner sc = new Scanner(System.in);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println();

			}
			System.out.println();

		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String args[] args public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							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);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							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);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println();

			}
			System.out.println();

		}

	}
}

