import java.util.Scanner;

public class Main{
	public static void main(String[]args) {
		 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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 }
		 System.out.println("");
		 }
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[]args) {
		 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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 }
		 System.out.println("");
		 }
	}
} Main public static void main(String[]args) {
		 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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 }
		 System.out.println("");
		 }
	} main {
		 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+j)%2==0) {
			    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+j)%2==0) {
			    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+j)%2==0) {
			    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+j)%2==0) {
			    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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 } {
			   for(int j=0 ; j<W ; j++) {
			    if((i+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 } for(int j=0 ; j<W ; j++) {
			    if((i+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   } int j=0 ; int j=0 ; j 0 j<W j W j++ j++ j {
			    if((i+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   } {
			    if((i+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   } if((i+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    } (i+j)%2==0 (i+j)%2 (i+j) i j 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 "" System.out.println("") System.out.println System.out System System.out "" String[]args args public class Main{
	public static void main(String[]args) {
		 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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 }
		 System.out.println("");
		 }
	}
} public class Main{
	public static void main(String[]args) {
		 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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 }
		 System.out.println("");
		 }
	}
} Main
import java.util.Scanner;

public class Main{
	public static void main(String[]args) {
		 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+j)%2==0) {
			    System.out.print('#');
		    }else {
			      System.out.print('.');
			    }
			   }
			   System.out.println("");
		 }
		 System.out.println("");
		 }
	}
}
