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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		System.out.println();             
		}             
		System.out.println(); 
		} true {
		int h = sc.nextInt();
		int w = sc.nextInt();             
		if (h == 0 && w == 0) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return; h == 0 && w == 0 h == 0 h 0 w == 0 w 0 return; for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		System.out.println();             
		} {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		System.out.println();             
		} for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		} int j = 0; int j = 0; j 0 j < w j w j++ j++ j {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		} {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		} System.out.print(((i + j) % 2 == 0)? '#' : '.') System.out.print System.out System System.out ((i + j) % 2 == 0)? '#' : '.' ((i + j) % 2 == 0) (i + j) % 2 (i + j) i j 2 0 '#' '.' 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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		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) return;            
		for (int i = 0; i < h; i++) {                 
		for (int j = 0; j < w; j++) {                     
		System.out.print(((i + j) % 2 == 0)? '#' : '.'); 
		}                 
		System.out.println();             
		}             
		System.out.println(); 
		}
        }
}