import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);

		while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);

		while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} Main public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);

		while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	} main {
		Scanner sc = new Scanner(System.in);

		while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		} true {
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		} final int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc final int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc if(H == 0 && W == 0){
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; 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 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){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);

		while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}

} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);

		while(true){
			final int H = sc.nextInt();
			final int W = sc.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					System.out.print((i + j) % 2 == 0 ? "#" : ".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}

}