import java.io.*;

class Main{
	public static void main(String args[]) throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		}
	}
} import java.io.*; io.* java class Main{
	public static void main(String args[]) throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		}
	}
} Main public static void main(String args[]) throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		}
	} main {
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		}
	} BufferedReader buf = new BufferedReader(new InputStreamReader(System.in)); buf new BufferedReader(new InputStreamReader(System.in)) while(true){
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		} true {
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		} String[] str = buf.readLine().split(" "); str buf.readLine().split(" ") buf.readLine().split buf.readLine() buf.readLine buf " " int H = Integer.parseInt(str[0]); H Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int W = Integer.parseInt(str[1]); W Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 if(W==0 && H==0)
				break; W==0 && H==0 W==0 W 0 H==0 H 0 break; for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} int i=1; int i=1; i 1 i<=H i H i++ i++ i {
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} {
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				} int j=1; int j=1; j 1 j<=W j W j++ j++ j {
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				} {
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				} if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print("."); i%2==1 && j%2==1 || i%2==0 && j%2==0 i%2==1 && j%2==1 i%2==1 i%2 i 2 1 j%2==1 j%2 j 2 1 i%2==0 && j%2==0 i%2==0 i%2 i 2 0 j%2==0 j%2 j 2 0 System.out.print("#") System.out.print System.out System System.out "#" 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
import java.io.*;

class Main{
	public static void main(String args[]) throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String[] str = buf.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);

			if(W==0 && H==0)
				break;

			for(int i=1; i<=H; i++){
				for(int j=1; j<=W; j++){
					if(i%2==1 && j%2==1 || i%2==0 && j%2==0)
						System.out.print("#");
					else
						System.out.print(".");
				}
				System.out.println();
			} 
			System.out.println();
		}
	}
}