import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		}
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		}
	} main {
		Scanner sc = new Scanner(System.in);
		while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		} true {
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		} int H=sc.nextInt(); H sc.nextInt() sc.nextInt sc int W=sc.nextInt(); W sc.nextInt() sc.nextInt sc if(H==0&&W==0) break; H==0&&W==0 H==0 H 0 W==0 W 0 break; for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			} int j=0; int j=0; j 0 j<(H-H%2)/2 j (H-H%2)/2 (H-H%2) H H%2 H 2 2 j++ j++ j {
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			} {
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			} for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	} int i=0; int i=0; i 0 i<(W-W%2)/2 i (W-W%2)/2 (W-W%2) W W%2 W 2 2 i++ i++ i {
			    	System.out.print("#.");
			    	} {
			    	System.out.print("#.");
			    	} System.out.print("#.") System.out.print System.out System System.out "#." if(W%2==1) System.out.print("#"); W%2==1 W%2 W 2 1 System.out.print("#") System.out.print System.out System System.out "#" System.out.println() System.out.println System.out System System.out for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		} int i=0; int i=0; i 0 i<(W-W%2)/2 i (W-W%2)/2 (W-W%2) W W%2 W 2 2 i++ i++ i {
		    		System.out.print(".#");
		    		} {
		    		System.out.print(".#");
		    		} System.out.print(".#") System.out.print System.out System System.out ".#" if(W%2==1) System.out.print("."); W%2==1 W%2 W 2 1 System.out.print(".") System.out.print System.out System System.out "." System.out.println() System.out.println System.out System System.out if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			} H%2==1 H%2 H 2 1 {
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			} for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	} int i=0; int i=0; i 0 i<(W-W%2)/2 i (W-W%2)/2 (W-W%2) W W%2 W 2 2 i++ i++ i {
			    	System.out.print("#.");
			    	} {
			    	System.out.print("#.");
			    	} System.out.print("#.") System.out.print System.out System System.out "#." if(W%2==1) System.out.print("#"); W%2==1 W%2 W 2 1 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){
		Scanner sc = new Scanner(System.in);
		while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		}
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		while(true){
			int H=sc.nextInt();
			int W=sc.nextInt();
			if(H==0&&W==0) break;
			for(int j=0;j<(H-H%2)/2;j++){
		    	for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
		    	for(int i=0;i<(W-W%2)/2;i++){
		    		System.out.print(".#");
		    		}
		    	if(W%2==1) System.out.print(".");
		    	System.out.println();
			}
			if(H%2==1){
				for(int i=0;i<(W-W%2)/2;i++){
			    	System.out.print("#.");
			    	}
		    	if(W%2==1) System.out.print("#");
		    	System.out.println();
			}
			System.out.println();
		}
	}
} Main
import java.util.Scanner;

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