import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args)throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main{
	public static void main(String[] args)throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	}
} Main public static void main(String[] args)throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	} main {
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	} InputStreamReader isr = new InputStreamReader(System.in); isr new InputStreamReader(System.in) BufferedReader reader = new BufferedReader(isr); reader new BufferedReader(isr) String string; string while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		} !(string = reader.readLine()).equals("0 0") (string = reader.readLine()).equals("0 0") (string = reader.readLine()).equals (string = reader.readLine()) string reader.readLine() reader.readLine reader "0 0" {
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		} for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			} int i = 0; int i = 0; i 0 i < Integer.parseInt(string.split(" ")[0]) i Integer.parseInt(string.split(" ")[0]) Integer.parseInt Integer string.split(" ")[0] string.split(" ") string.split string " " 0 i++ i++ i {
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			} {
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			} for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} int j = 0; int j = 0; j 0 j < Integer.parseInt(string.split(" ")[1]) j Integer.parseInt(string.split(" ")[1]) Integer.parseInt Integer string.split(" ")[1] string.split(" ") string.split string " " 1 j++ j++ j {
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} {
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					} i % 2 == 0 i % 2 i 2 0 {
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					} if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						} j % 2 == 0 j % 2 j 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 "." {
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					} if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						} j % 2 == 0 j % 2 j 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 reader.close() reader.close reader String[] args args public class Main{
	public static void main(String[] args)throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	}
} public class Main{
	public static void main(String[] args)throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args)throws IOException{
		InputStreamReader isr = new InputStreamReader(System.in);
		BufferedReader reader = new BufferedReader(isr);
		String string;
		while(!(string = reader.readLine()).equals("0 0")){
			for(int i = 0; i < Integer.parseInt(string.split(" ")[0]); i++){
				for(int j = 0; j < Integer.parseInt(string.split(" ")[1]); j++){
					if(i % 2 == 0){
						if(j % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
		}
		reader.close();
	}
}