import java.util.Scanner;
class Main {
	public void kami() {
		Scanner sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		}
		
	
	}

	public static void main(String[] args) {

		new Main().kami();
	}

} import java.util.Scanner; Scanner java.util class Main {
	public void kami() {
		Scanner sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		}
		
	
	}

	public static void main(String[] args) {

		new Main().kami();
	}

} Main public void kami() {
		Scanner sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		}
		
	
	} kami {
		Scanner sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		}
		
	
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		} H != 0 || W != 0 H != 0 H 0 W != 0 W 0 {
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		} for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			} int j = 1; int j = 1; j 1 j <= H j H j++ j++ j {
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			} {
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			} for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} int i = 1; int i = 1; i 1 i <= W i W i++ i++ i {
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} {
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					} j % 2 == 0 j % 2 j 2 0 {
						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 "." {
						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 System.out.println() System.out.println System.out System System.out H = sc.nextInt() H sc.nextInt() sc.nextInt sc W = sc.nextInt() W sc.nextInt() sc.nextInt sc public static void main(String[] args) {

		new Main().kami();
	} main {

		new Main().kami();
	} new Main().kami() new Main().kami new Main() String[] args args
import java.util.Scanner;
class Main {
	public void kami() {
		Scanner sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		}
		
	
	}

	public static void main(String[] args) {

		new Main().kami();
	}

}