//Structured Program I - Print a Frame
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

		String input;
		
		 while (!(input = in.readLine()).equals("0 0")) {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

		String input;
		
		 while (!(input = in.readLine()).equals("0 0")) {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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 {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

		String input;
		
		 while (!(input = in.readLine()).equals("0 0")) {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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 {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

		String input;
		
		 while (!(input = in.readLine()).equals("0 0")) {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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();
			 
		 }

	} BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) String input; input while (!(input = in.readLine()).equals("0 0")) {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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();
			 
		 } !(input = in.readLine()).equals("0 0") (input = in.readLine()).equals("0 0") (input = in.readLine()).equals (input = in.readLine()) input in.readLine() in.readLine in "0 0" {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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();
			 
		 } String[] HW = input.split(" "); HW input.split(" ") input.split input " " int H = Integer.parseInt(HW[0]); H Integer.parseInt(HW[0]) Integer.parseInt Integer HW[0] HW 0 int W = Integer.parseInt(HW[1]); W Integer.parseInt(HW[1]) Integer.parseInt Integer HW[1] HW 1 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.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 String[] args args
//Structured Program I - Print a Frame
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Main {

	public static void main(String[] args) throws IOException {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

		String input;
		
		 while (!(input = in.readLine()).equals("0 0")) {

			 String[] HW = input.split(" ");

			 int H = Integer.parseInt(HW[0]);
			 int W = Integer.parseInt(HW[1]);

			 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();
			 
		 }

	}
}