import java.util.Scanner;

public class Main {
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	}
	
	static void evenNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
	
	static void oddNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	}
	
	static void evenNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
	
	static void oddNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
} Main public static void main(String args[]){
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	} main {
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int H H W; W for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		} ; {

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		} {

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		} H = scan.nextInt() H scan.nextInt() scan.nextInt scan W = scan.nextInt() W scan.nextInt() scan.nextInt scan 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++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			} int i = 0; int i = 0; i 0 i < H i H i++ i++ i {
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			} {
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			} if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				} i % 2 != 0 i % 2 i 2 0 {
					evenNumberLine(W);
				} evenNumberLine(W) evenNumberLine W {
					oddNumberLine(W);
				} oddNumberLine(W) oddNumberLine W System.out.println() System.out.println System.out System System.out String args[] args static void evenNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	} evenNumberLine {
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	} for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		} int i = 0; int i = 0; i 0 i < w i w i++ i++ i {
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		} {
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		} if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			} i % 2 != 0 i % 2 i 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 int w w static void oddNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	} oddNumberLine {
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	} for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		} int i = 0; int i = 0; i 0 i < w i w i++ i++ i {
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		} {
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		} if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			} i % 2 == 0 i % 2 i 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 int w w public class Main {
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	}
	
	static void evenNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
	
	static void oddNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
} public class Main {
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	}
	
	static void evenNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
	
	static void oddNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in); 
		
		int H, W;
		
		for(;;){

			H = scan.nextInt();
			W = scan.nextInt();
			
			if(H == 0 && W == 0){
				break;
			}
			for(int i = 0; i < H; i++){
				if(i % 2 != 0){
					evenNumberLine(W);
				}else{
					oddNumberLine(W);
				}
			}
			System.out.println();
		}
	}
	
	static void evenNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 != 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
	
	static void oddNumberLine(int w){
		for(int i = 0; i < w; i++){
			if(i % 2 == 0){
				System.out.print("#");
			}else{
				System.out.print(".");
			}
		}
		System.out.println();
	}
}