import java.util.*;

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

class Main{
	public static void main(String[] args){
		Scanner sr = new Scanner(System.in);
		while(true){
			int h = sr.nextInt();
			int w = sr.nextInt();
			if(h==0&&w==0) break;
			for(int y=0; y<h; y++){
				for(int x=0; x<w; x++){
					if((x+y)%2==0){
						System.out.print("#");
					}else{
						System.out.print(".");
					}
				}
				System.out.println();
			}
		System.out.println();
		}
	}
}