import java.util.Scanner;

public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	}
} Main public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int h h w w i i j; j boolean state = false; state false h = sc.nextInt() h sc.nextInt() sc.nextInt sc w = sc.nextInt() w sc.nextInt() sc.nextInt sc while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		} h != 0 && w != 0 h != 0 h 0 w != 0 w 0 {
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		} for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			} i = 0; i = 0 i 0 i < h i h i++ i++ i {
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			} {
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			} if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				} i % 2 == 0 i % 2 i 2 0 {
					state = false;
				} state = false state false {
					state = true;
				} state = true state true for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				} j = 0; j = 0 j 0 j < w j w j++ j++ j {
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				} {
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				} if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					} !state state {
						System.out.print("#");
						state = true;
					} System.out.print("#") System.out.print System.out System System.out "#" state = true state true {
						System.out.print(".");
						state = false;
					} System.out.print(".") System.out.print System.out System System.out "." state = false state false System.out.println("") System.out.println System.out System System.out "" System.out.println("") System.out.println System.out System System.out "" h = sc.nextInt() h sc.nextInt() sc.nextInt sc w = sc.nextInt() w sc.nextInt() sc.nextInt sc String [] args args public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	}
} public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	}
} Main
import java.util.Scanner;

public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int h,w,i,j;
		boolean state = false;
		h = sc.nextInt();
		w = sc.nextInt();
		while(h != 0 && w != 0){
			for(i = 0; i < h; i++){
				if(i % 2 == 0){
					state = false;
				}else{
					state = true;
				}
				for(j = 0; j < w; j++){
					if(!state){
						System.out.print("#");
						state = true;
					}else{
						System.out.print(".");
						state = false;
					}
				}
				System.out.println("");
			}
			System.out.println("");
			h = sc.nextInt();
			w = sc.nextInt();
		}
	}
}