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