import java.io.File;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.Scanner;

public class Main {
 
	public static void main(String[] args) throws IOException {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}
} import java.io.File; File java.io import java.io.IOException; IOException java.io import java.util.ArrayDeque; ArrayDeque java.util import java.util.ArrayList; ArrayList java.util import java.util.Deque; Deque java.util import java.util.Scanner; Scanner java.util public class Main {
 
	public static void main(String[] args) throws IOException {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}
} Main public static void main(String[] args) throws IOException {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		}
	} main {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				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) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		} true {
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				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) break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				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++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			} {
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			} for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				} int j = 0; int j = 0; j 0 j < W j W j++ j++ j {
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				} {
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				} if(i % 2 == j % 2) System.out.print("#");
					else System.out.print("."); i % 2 == j % 2 i % 2 i 2 j % 2 j 2 System.out.print("#") System.out.print System.out System System.out "#" 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 public class Main {
 
	public static void main(String[] args) throws IOException {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}
} public class Main {
 
	public static void main(String[] args) throws IOException {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}
} Main
import java.io.File;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.Scanner;

public class Main {
 
	public static void main(String[] args) throws IOException {
		//File file = new File("input.txt");
		//Scanner sc = new Scanner(file);
		
		Scanner sc = new Scanner(System.in);
		
		while(true){
			int H = sc.nextInt();
			int W = sc.nextInt();
			if(H == 0 && W == 0) break;
			for(int i = 0; i < H; i++){
				for(int j = 0; j < W; j++){
					if(i % 2 == j % 2) System.out.print("#");
					else System.out.print(".");
				}
				System.out.println();
			}
			System.out.println();
		}
	}
}
