import java.util.Scanner;
import java.lang.StringBuilder;
public class Main {
	public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	}
} import java.util.Scanner; Scanner java.util import java.lang.StringBuilder; StringBuilder java.lang public class Main {
	public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	}
} Main public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	} main {
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) StringBuilder bu = new StringBuilder(); bu new StringBuilder() int h h w; w while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		} (h=sc.nextInt())!=0&&(w=sc.nextInt())!=0 (h=sc.nextInt())!=0 (h=sc.nextInt()) h sc.nextInt() sc.nextInt sc 0 (w=sc.nextInt())!=0 (w=sc.nextInt()) w sc.nextInt() sc.nextInt sc 0 {
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		} for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			} int i=0; int i=0; i 0 i<h i h i++ i++ i {
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			} {
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			} for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				} int o=0; int o=0; o 0 o<w o w o++ o++ o {
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				} {
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				} if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					} (i+o)%2==0 (i+o)%2 (i+o) i o 2 0 {
						bu.append("#");
					} bu.append("#") bu.append bu "#" {
						bu.append(".");
					} bu.append(".") bu.append bu "." bu.append("\n") bu.append bu "\n" bu.append("\n") bu.append bu "\n" System.out.print(bu) System.out.print System.out System System.out bu String[] args args public class Main {
	public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	}
} public class Main {
	public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	}
} Main
import java.util.Scanner;
import java.lang.StringBuilder;
public class Main {
	public static void main(String[] args) throws Exception{
		Scanner sc = new Scanner(System.in);
		StringBuilder bu = new StringBuilder();
		int h,w;
		while((h=sc.nextInt())!=0&&(w=sc.nextInt())!=0){
			for(int i=0;i<h;i++){
				for(int o=0;o<w;o++){
					if((i+o)%2==0){
						bu.append("#");
					}else{
						bu.append(".");
					}
				}
				bu.append("\n");
			}
			bu.append("\n");
		}
		System.out.print(bu);
	}
}