import java.util.Scanner;
public class Main {
	public static void main(String[] args) {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	}

} Main public static void main(String[] args) {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	} main {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int h =sc.nextInt(); h sc.nextInt() sc.nextInt sc int w=sc.nextInt(); w sc.nextInt() sc.nextInt sc while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		} true {
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		} if(h==0 && w==0) break; h==0 && w==0 h==0 h 0 w==0 w 0 break; StringBuilder sh1 = new StringBuilder(); sh1 new StringBuilder() for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        } int i = 0; int i = 0; i 0 i < w/2 i w/2 w 2 i++ i++ i {
	            sh1.append("#.");
	        } {
	            sh1.append("#.");
	        } sh1.append("#.") sh1.append sh1 "#." if(sh1.length()<w) sh1.append("#"); sh1.length()<w sh1.length() sh1.length sh1 w sh1.append("#") sh1.append sh1 "#" StringBuilder sh2 = new StringBuilder(); sh2 new StringBuilder() for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        } int i = 0; int i = 0; i 0 i < w/2 i w/2 w 2 i++ i++ i {
	            sh2.append(".#");
	        } {
	            sh2.append(".#");
	        } sh2.append(".#") sh2.append sh2 ".#" if(sh2.length()<w) sh2.append("."); sh2.length()<w sh2.length() sh2.length sh2 w sh2.append(".") sh2.append sh2 "." for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        } int i=0; int i=0; i 0 i<h i h i++ i++ i {
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        } {
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        } if(i%2==0) System.out.println(sh1); i%2==0 i%2 i 2 0 System.out.println(sh1) System.out.println System.out System System.out sh1 if(i%2==1) System.out.println(sh2); i%2==1 i%2 i 2 1 System.out.println(sh2) System.out.println System.out System System.out sh2 System.out.println() System.out.println System.out System System.out h =sc.nextInt() h sc.nextInt() sc.nextInt sc w=sc.nextInt() w sc.nextInt() sc.nextInt sc String[] args args public class Main {
	public static void main(String[] args) {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	}

} public class Main {
	public static void main(String[] args) {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	}

} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {

		Scanner sc=new Scanner(System.in);
		int h =sc.nextInt();
		int w=sc.nextInt();
	    
		while(true){
			if(h==0 && w==0) break;
			StringBuilder sh1 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh1.append("#.");
	        }
	        if(sh1.length()<w) sh1.append("#");
	
	        StringBuilder sh2 = new StringBuilder();
	        for (int i = 0; i < w/2; i++) {
	            sh2.append(".#");
	        }
	        if(sh2.length()<w) sh2.append(".");
	
	        for(int i=0;i<h;i++){
	        	if(i%2==0) System.out.println(sh1);
	        	if(i%2==1) System.out.println(sh2);
	        }
	        System.out.println();
	        
			h =sc.nextInt();
			w=sc.nextInt();
		}
	}

}