import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	}
} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	} main {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		} ; {
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		} {
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		} int H =  sc.nextInt(); H sc.nextInt() sc.nextInt sc int W =  sc.nextInt(); W sc.nextInt() sc.nextInt sc int n = 0; n 0 int a = 0; a 0 if(W%2==1)a=1; //?\???°?????? W%2==1 W%2 W 2 1 a=1 a 1 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(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    } int i=0; int i=0; i 0 i<H i H i++ i++ i {
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    } {
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    } for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	} int j=0; int j=0; j 0 j<W j W j++ j++ j {
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	} {
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	} if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		} n%2==0 n%2 n 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 "." n++ n System.out.println() System.out.println System.out System System.out if(a==0)n++; a==0 a 0 n++ n System.out.println() System.out.println System.out System System.out String[] args args public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	}
} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			int H =  sc.nextInt();
		    int W =  sc.nextInt();
		    int n = 0;
		    int a = 0;     //??¶??°??????
		    if(W%2==1)a=1; //?\???°??????
		    if(H==0 && W==0) break;
		    for(int i=0; i<H; i++){
		    	for(int j=0; j<W; j++){
		    		if(n%2==0){
		    			System.out.print("#");
		    		}else{
		    			System.out.print(".");
		    		}
		    		n++;
		    	}
		    	System.out.println();
			    if(a==0)n++;
		    }
	    	System.out.println();
		}
	}
}