import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	}
} Main public static void main(String[] args) {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	} main {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	} Scanner n=new Scanner(System.in); n new Scanner(System.in) int a=n.nextInt(); a n.nextInt() n.nextInt n int b=n.nextInt(); b n.nextInt() n.nextInt n StringBuilder sb=new StringBuilder(""); sb new StringBuilder("") while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		} a!=0 || b!=0 a!=0 a 0 b!=0 b 0 {
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		} sb=new StringBuilder("") sb new StringBuilder("") for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				} int c=0; int c=0; c 0 c<a c a c++ c++ c {
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				} {
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				} if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					} (c%2)==0 (c%2) c 2 0 {
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					} for (int d=0;d<b;d++){
							sb.append("#");
						} int d=0; int d=0; d 0 d<b d b d++ d++ d {
							sb.append("#");
						} {
							sb.append("#");
						} sb.append("#") sb.append sb "#" for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						} int e=1; int e=1; e 1 e<b e b e+=2 e+=2 e 2 {
							sb.replace(e,e+1,".");
						} {
							sb.replace(e,e+1,".");
						} sb.replace(e,e+1,".") sb.replace sb e e+1 e 1 "." {
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					} for (int f=0;f<b;f++){
							sb.append(".");
						} int f=0; int f=0; f 0 f<b f b f++ f++ f {
							sb.append(".");
						} {
							sb.append(".");
						} sb.append(".") sb.append sb "." for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						} int g=1; int g=1; g 1 g<b g b g+=2 g+=2 g 2 {
							sb.replace(g,g+1,"#");
						} {
							sb.replace(g,g+1,"#");
						} sb.replace(g,g+1,"#") sb.replace sb g g+1 g 1 "#" System.out.println(sb) System.out.println System.out System System.out sb sb=new StringBuilder("") sb new StringBuilder("") a=n.nextInt() a n.nextInt() n.nextInt n b=n.nextInt() b n.nextInt() n.nextInt n System.out.println(sb) System.out.println System.out System System.out sb String[] args args public class Main {

	public static void main(String[] args) {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	}
} public class Main {

	public static void main(String[] args) {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	}
} Main
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner n=new Scanner(System.in);
		int a=n.nextInt();int b=n.nextInt();
		StringBuilder sb=new StringBuilder("");
		while (a!=0 || b!=0){
			sb=new StringBuilder("");
				for (int c=0;c<a;c++){
					if ((c%2)==0){
						for (int d=0;d<b;d++){
							sb.append("#");
						}
						for (int e=1;e<b;e+=2){
							sb.replace(e,e+1,".");
						}
					}else{
						for (int f=0;f<b;f++){
							sb.append(".");
						}
						for (int g=1;g<b;g+=2){
							sb.replace(g,g+1,"#");
						}
					}
					System.out.println(sb);
					sb=new StringBuilder("");
				}
			a=n.nextInt();b=n.nextInt();
			System.out.println(sb);
		}
	}
}