import java.util.Scanner;

class Main{
    public static void main(String[] args){
        int H,W;
    	//?¨??????\??????????????????????????§????????????
		Scanner scanner = new Scanner(System.in);
		
		while(true){
			H = scanner.nextInt();
			W = scanner.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.close();
    }
} import java.util.Scanner; Scanner java.util class Main{
    public static void main(String[] args){
        int H,W;
    	//?¨??????\??????????????????????????§????????????
		Scanner scanner = new Scanner(System.in);
		
		while(true){
			H = scanner.nextInt();
			W = scanner.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.close();
    }
} Main public static void main(String[] args){
        int H,W;
    	//?¨??????\??????????????????????????§????????????
		Scanner scanner = new Scanner(System.in);
		
		while(true){
			H = scanner.nextInt();
			W = scanner.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.close();
    } main {
        int H,W;
    	//?¨??????\??????????????????????????§????????????
		Scanner scanner = new Scanner(System.in);
		
		while(true){
			H = scanner.nextInt();
			W = scanner.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.close();
    } int H H W; W Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while(true){
			H = scanner.nextInt();
			W = scanner.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 {
			H = scanner.nextInt();
			W = scanner.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();
		} H = scanner.nextInt() H scanner.nextInt() scanner.nextInt scanner W = scanner.nextInt() W scanner.nextInt() scanner.nextInt scanner if(H == 0 && W == 0){
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} 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 scanner.close() scanner.close scanner String[] args args
import java.util.Scanner;

class Main{
    public static void main(String[] args){
        int H,W;
    	//?¨??????\??????????????????????????§????????????
		Scanner scanner = new Scanner(System.in);
		
		while(true){
			H = scanner.nextInt();
			W = scanner.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.close();
    }
}