import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	}
} Main public static void main(String[] args){
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	} main {
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	} Scanner std = new Scanner(System.in); std new Scanner(System.in) while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		} true {
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		} int h = Integer.parseInt(std.next()); h Integer.parseInt(std.next()) Integer.parseInt Integer std.next() std.next std int w = Integer.parseInt(std.next()); w Integer.parseInt(std.next()) Integer.parseInt Integer std.next() std.next std if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break; h!=0 && w!=0 h!=0 h 0 w!=0 w 0 {
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			} String line = ""; line "" for(int m=1; m<=w/2+1; m++){
					line += "#.";
				} int m=1; int m=1; m 1 m<=w/2+1 m w/2+1 w/2 w 2 1 m++ m++ m {
					line += "#.";
				} {
					line += "#.";
				} line += "#." line "#." for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				} int n=1; int n=1; n 1 n<=h n h n++ n++ n {
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				} {
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				} if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					} n%2==1 n%2 n 2 1 {
						System.out.println(line.substring(0, w));
					} System.out.println(line.substring(0, w)) System.out.println System.out System System.out line.substring(0, w) line.substring line 0 w {
						System.out.println(line.substring(1, w+1));
					} System.out.println(line.substring(1, w+1)) System.out.println System.out System System.out line.substring(1, w+1) line.substring line 1 w+1 w 1 System.out.println() System.out.println System.out System System.out break; String[] args args public class Main {
	public static void main(String[] args){
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	}
} public class Main {
	public static void main(String[] args){
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner std = new Scanner(System.in);
		while(true){
			int h = Integer.parseInt(std.next());
			int w = Integer.parseInt(std.next());
			if(h!=0 && w!=0){
				String line = "";
				for(int m=1; m<=w/2+1; m++){
					line += "#.";
				}
				for(int n=1; n<=h; n++){
					if(n%2==1){
						System.out.println(line.substring(0, w));
					}else{
						System.out.println(line.substring(1, w+1));
					}
				}
				System.out.println();
			}else break;
		}
	}
}