import java.util.*;

public class Main {

	public static void  main(String[] args) {
		scan();
		
		
		
	}
	
	public static void scan() {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	}

	public static void draw(int  H , int W) {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	}
	
} import java.util.*; util.* java public class Main {

	public static void  main(String[] args) {
		scan();
		
		
		
	}
	
	public static void scan() {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	}

	public static void draw(int  H , int W) {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	}
	
} Main public static void  main(String[] args) {
		scan();
		
		
		
	} main {
		scan();
		
		
		
	} scan() scan String[] args args public static void scan() {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	} scan {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		} true {
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		} int H = scanner.nextInt(); H scanner.nextInt() scanner.nextInt scanner int W = scanner.nextInt(); W scanner.nextInt() scanner.nextInt scanner if(H == 0 && W == 0){
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; draw(H , W) draw H W System.out.println("") System.out.println System.out System System.out "" scanner.close() scanner.close scanner return; public static void draw(int  H , int W) {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	} draw {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	} for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		} int y = 0 ; int y = 0 ; y 0 y < H y H y++ y++ y {	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		} {	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		} for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			} int x = 0 ; int x = 0 ; x 0 x < W x W x++ x++ x {
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			} {
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			} if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				} y % 2 == 0 y % 2 y 2 0 {
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				} if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					} x % 2 == 0 x % 2 x 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(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				} if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					} x % 2 != 0 x % 2 x 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 "" return ; int  H H int W W public class Main {

	public static void  main(String[] args) {
		scan();
		
		
		
	}
	
	public static void scan() {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	}

	public static void draw(int  H , int W) {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	}
	
} public class Main {

	public static void  main(String[] args) {
		scan();
		
		
		
	}
	
	public static void scan() {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	}

	public static void draw(int  H , int W) {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	}
	
} Main
import java.util.*;

public class Main {

	public static void  main(String[] args) {
		scan();
		
		
		
	}
	
	public static void scan() {
		Scanner scanner = new Scanner(System.in);
		while(true){
			int H = scanner.nextInt();
			int W = scanner.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			draw(H , W);
			System.out.println("");
		}	
		scanner.close();
		return;
	}

	public static void draw(int  H , int W) {
		for(int y = 0 ; y < H ; y++){	
			for(int x = 0 ; x < W ; x++){
				if(y % 2 == 0){
					if(x % 2 == 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}
				else{
					if(x % 2 != 0){
						System.out.print("#");
					}
					else{
						System.out.print(".");
					}
				}	
			}
			System.out.println("");
		}
		return ;
	}
	
}