import java.util.Scanner;

public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	}
} Main @SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	} main {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		} scan.hasNext() scan.hasNext scan {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		} int H = scan.nextInt(); H scan.nextInt() scan.nextInt scan int W = scan.nextInt(); W scan.nextInt() scan.nextInt scan if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; {
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			} String str = ""; str "" for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				} int i = 1; int i = 1; i 1 i <= W + 1 i W + 1 W 1 i++ i++ i {
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				} {
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				} if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					} i % 2 == 1 i % 2 i 2 1 {
						str += "#";
					} str += "#" str "#" {
						str += ".";
					} str += "." str "." String odd_str = str.substring(0, str.length() - 1); odd_str str.substring(0, str.length() - 1) str.substring str 0 str.length() - 1 str.length() str.length str 1 String even_str = str.substring(1); even_str str.substring(1) str.substring str 1 for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				} int i = 1; int i = 1; i 1 i <= H i H i++ i++ i {
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				} {
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				} if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					} i % 2 == 1 i % 2 i 2 1 {
						System.out.println(odd_str);
					} System.out.println(odd_str) System.out.println System.out System System.out odd_str {
						System.out.println(even_str);
					} System.out.println(even_str) System.out.println System.out System System.out even_str System.out.println() System.out.println System.out System System.out String[] args args public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	}
} public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	}
} Main
import java.util.Scanner;

public class Main {
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(scan.hasNext()){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}else{
				String str = "";
				for(int i = 1; i <= W + 1; i++){
					if(i % 2 == 1){
						str += "#";
					}else{
						str += ".";
					}
				}
				String odd_str = str.substring(0, str.length() - 1);
				String even_str = str.substring(1);
				for(int i = 1; i <= H; i++){
					if(i % 2 == 1){
						System.out.println(odd_str);
					}else{
						System.out.println(even_str);
					}
				}
				System.out.println();
			}
		}
	}
}