import java.util.*;
public class Main{
	public static void main(String[]agrs){
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		}
	}
} import java.util.*; util.* java public class Main{
	public static void main(String[]agrs){
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		}
	}
} Main public static void main(String[]agrs){
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		}
	} main {
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 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) int w w h; h while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		} sc.hasNextInt() sc.hasNextInt sc {
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		} h=sc.nextInt() h sc.nextInt() sc.nextInt sc w=sc.nextInt() w sc.nextInt() sc.nextInt sc if(w==0||h==0)break; w==0||h==0 w==0 w 0 h==0 h 0 break; for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 } int i=0; int i=0; i 0 i<h/2 i h/2 h 2 i++ i++ i {
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 } {
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 } for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 } int j=0; int j=0; j 0 j<w/2 j w/2 w 2 j++ j++ j {
				 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 j=0;j<w/2;j++){
				 System.out.print(".#");
				 } int j=0; int j=0; j 0 j<w/2 j w/2 w 2 j++ j++ j {
				 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 j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 } h%2==1 h%2 h 2 1 {
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 } for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 } int j=0; int j=0; j 0 j<w/2 j w/2 w 2 j++ j++ j {
					 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[]agrs agrs public class Main{
	public static void main(String[]agrs){
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		}
	}
} public class Main{
	public static void main(String[]agrs){
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		}
	}
} Main
import java.util.*;
public class Main{
	public static void main(String[]agrs){
		Scanner sc=new Scanner(System.in);
		int w,h;
		while(sc.hasNextInt()){
		 h=sc.nextInt();
		 w=sc.nextInt();
		 if(w==0||h==0)break;
		 for(int i=0;i<h/2;i++){
			 for(int j=0;j<w/2;j++){
				 System.out.print("#.");
				 
				 }if(w%2==1)System.out.print("#");
				 System.out.println();
			 for(int j=0;j<w/2;j++){
				 System.out.print(".#");
				 } if(w%2==1)System.out.print(".");
                  System.out.println();
			 }if(h%2==1){
				 for(int j=0;j<w/2;j++){
					 System.out.print("#.");
					 
				 }
				 if(w%2==1)System.out.print("#");
				 System.out.println();
				 
		 }System.out.println();
			
		}
	}
}