import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	}

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

} Main public static void main(String[] args){
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	} main {
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	} Scanner a = new Scanner(System.in); a new Scanner(System.in) int h =1; h 1 int w = 1; w 1 while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		} h > 0 && w > 0 h > 0 h 0 w > 0 w 0 {
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		} h = a.nextInt() h a.nextInt() a.nextInt a w = a.nextInt() w a.nextInt() a.nextInt a for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			} int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			} {
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			} int count = 0; count 0 for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				} int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				} {
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				} if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					} (i % 2) == 0 (i % 2) i 2 0 {
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					} System.out.print("#") System.out.print System.out System System.out "#" count++ count if(count == (w))
							break; count == (w) count (w) break; System.out.print(".") System.out.print System.out System System.out "." count++ count if(count == (w))
							break; count == (w) count (w) break; {
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					} System.out.print(".") System.out.print System.out System System.out "." count++ count if(count == (w))
							break; count == (w) count (w) break; System.out.print("#") System.out.print System.out System System.out "#" count++ count if(count == (w))
							break; count == (w) count (w) break; if(h != 0 && w != 0)
					System.out.println(); h != 0 && w != 0 h != 0 h 0 w != 0 w 0 System.out.println() System.out.println System.out System System.out if(h != 0 && w != 0)
				System.out.println(); h != 0 && w != 0 h != 0 h 0 w != 0 w 0 System.out.println() System.out.println System.out System System.out String[] args args public class Main {
	public static void main(String[] args){
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	}

} public class Main {
	public static void main(String[] args){
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				int count = 0;
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						count++;
						if(count == (w))
							break;
						System.out.print(".");
						count++;
						if(count == (w))
							break;
					}else{
						System.out.print(".");
						count++;
						if(count == (w))
							break;
						System.out.print("#");
						count++;
						if(count == (w))
							break;
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	}

}