import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args)throws IOException {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
	public static void main(String[] args)throws IOException {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	}
} Main public static void main(String[] args)throws IOException {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	} main {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	} BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in)); bufferedReader new BufferedReader(new InputStreamReader(System.in)) while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 } true {
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 } String [] str = bufferedReader.readLine().split(" "); str bufferedReader.readLine().split(" ") bufferedReader.readLine().split bufferedReader.readLine() bufferedReader.readLine bufferedReader " " Integer hInteger = Integer.parseInt(str[0]); hInteger Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 Integer wInteger = Integer.parseInt(str[1]); wInteger Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 StringBuffer stringBuffer = new StringBuffer(); stringBuffer new StringBuffer() if(hInteger == 0 && wInteger == 0){
				 break;
			 } hInteger == 0 && wInteger == 0 hInteger == 0 hInteger 0 wInteger == 0 wInteger 0 {
				 break;
			 } break; for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 } int i = 0; int i = 0; i 0 i < hInteger i hInteger i++ i++ i {
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 } {
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 } for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  } int j = 0; int j = 0; j 0 j < wInteger j wInteger j++ j++ j {
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  } {
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  } stringBuffer.append((i + j) % 2 == 0 ? "#" : ".") stringBuffer.append stringBuffer (i + j) % 2 == 0 ? "#" : "." (i + j) % 2 == 0 (i + j) % 2 (i + j) i j 2 0 "#" "." stringBuffer.append("\n") stringBuffer.append stringBuffer "\n" System.out.println(stringBuffer) System.out.println System.out System System.out stringBuffer String[] args args public class Main {
	public static void main(String[] args)throws IOException {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	}
} public class Main {
	public static void main(String[] args)throws IOException {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args)throws IOException {
		 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
		 while(true){
			 String [] str = bufferedReader.readLine().split(" ");
			 Integer hInteger = Integer.parseInt(str[0]);
			 Integer wInteger = Integer.parseInt(str[1]);
			 
			 StringBuffer stringBuffer = new StringBuffer();
		 
			 if(hInteger == 0 && wInteger == 0){
				 break;
			 }
			 for(int i = 0; i < hInteger; i++){
				 for(int j = 0; j < wInteger; j++){
					 stringBuffer.append((i + j) % 2 == 0 ? "#" : ".");
					  }
				 stringBuffer.append("\n");
				 
			 }	 
			 System.out.println(stringBuffer);
		 }
		 
	}
}