import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
 
 		while(true){
 			int w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			}
 			System.out.println("");
 		}
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
 
 		while(true){
 			int w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						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 w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			}
 			System.out.println("");
 		}
	} main {
		Scanner sc = new Scanner(System.in);
 
 		while(true){
 			int w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						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 w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			}
 			System.out.println("");
 		} true {
 			int w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			}
 			System.out.println("");
 		} int w = sc.nextInt(); w sc.nextInt() sc.nextInt sc int h = sc.nextInt(); h sc.nextInt() sc.nextInt sc if(h == 0 && w == 0){break;} h == 0 && w == 0 h == 0 h 0 w == 0 w 0 {break;} break; for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			} int i = 1; int i = 1; i 1 i <= w i w i++ i++ i {
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			} {
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			} for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				} int j = 1; int j = 1; j 1 j <= h j h j++ j++ j {
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				} {
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				} if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					} (i + j) % 2 == 1 (i + j) % 2 (i + j) i j 2 1 {
 						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 w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						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 w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			}
 			System.out.println("");
 		}
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
 
 		while(true){
 			int w = sc.nextInt();
 			int h = sc.nextInt(); 			

 			if(h == 0 && w == 0){break;}

 			for(int i = 1; i <= w; i++){
 				for(int j = 1; j <= h; j++){
 					if((i + j) % 2 == 1){
 						System.out.print(".");
 					}else{
 						System.out.print("#");
 					}
 				}
 	 			System.out.println("");
 			}
 			System.out.println("");
 		}
	}
}