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