public class Main {


		public static void main(String[] args) {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		}
}	 public class Main {


		public static void main(String[] args) {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		}
} Main public static void main(String[] args) {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		} main {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		} java.util.Scanner scan = new java.util.Scanner(System.in); scan new java.util.Scanner(System.in) int h h w w i i t; t while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		} true {
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}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; if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		} 1 <= h && h <= 300 && 1 <= w && w <= 300 1 <= w 1 <= h && h <= 300 && 1 <= w && w <= 300 1 <= h 1 h h <= 300 h 300 1 <= w 1 w w <= 300 w 300 {
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		} for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			} i = 1; i = 1 i 1 i <= h i h i++ i++ i {
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			} {
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			} for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			} t = 1; t = 1 t 1 t <= w t w t++ t++ t {
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			} {
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			} if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				} t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0 t % 2 != 0 && i % 2 != 0 t % 2 != 0 t % 2 t 2 0 i % 2 != 0 i % 2 i 2 0 t % 2 == 0 && i % 2 == 0 t % 2 == 0 t % 2 t 2 0 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 "" String[] args args public class Main {


		public static void main(String[] args) {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		}
} public class Main {


		public static void main(String[] args) {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		}
} Main
public class Main {


		public static void main(String[] args) {
		java.util.Scanner scan = new java.util.Scanner(System.in);
		int h, w, i, t;
		
while(true){
		h = scan.nextInt();
		w = scan.nextInt();
		
		if(h == 0 && w == 0){
				break;
			}
		if(1 <= h && h <= 300 && 1 <= w && w <= 300){
			for(i = 1; i <= h ; i++){
			for(t = 1; t <= w ; t++){
				if(t % 2 != 0 && i % 2 != 0 || t % 2 == 0 && i % 2 == 0){
				System.out.print("#");
				}else{
					
					System.out.print(".");
				}
			}System.out.println("");
			
			}System.out.println("");
		
		
		}
		
		}
		}
}	