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;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	}
	static void printFrame (int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			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;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	}
	static void printFrame (int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			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;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		while (true) {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0) break;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	} 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;
			printFrame(a, b);
			System.out.println();
		} true {
			int a = sc.nextInt();
			int b = sc.nextInt();
			if (a == 0 && b == 0) break;
			printFrame(a, b);
			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; printFrame(a, b) printFrame a b System.out.println() System.out.println System.out System System.out sc.close() sc.close sc String[] args args static void printFrame (int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			System.out.println();
		}
	} printFrame {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			System.out.println();
		}
	} for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			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++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			System.out.println();
		} {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			System.out.println();
		} for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			} int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			} {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			} System.out.print((i + j) % 2 == 0 ? "#" : ".") System.out.print System.out System System.out (i + j) % 2 == 0 ? "#" : "." (i + j) % 2 == 0 (i + j) % 2 (i + j) i j 2 0 "#" "." System.out.println() System.out.println System.out System System.out int h h int w w 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;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	}
	static void printFrame (int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			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;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	}
	static void printFrame (int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			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;
			printFrame(a, b);
			System.out.println();
		}
		sc.close();
	}
	static void printFrame (int h, int w) {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((i + j) % 2 == 0 ? "#" : ".");
			}
			System.out.println();
		}
	}
}