import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		}
} Main public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		} main {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) StringBuilder sb=new StringBuilder(""); sb new StringBuilder("") int H=sc.nextInt() H sc.nextInt() sc.nextInt sc W=sc.nextInt(); W sc.nextInt() sc.nextInt sc while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		} H!=0||W!=0 H!=0 H 0 W!=0 W 0 {
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		} for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			} int a=1; int a=1; a 1 a<=H a H a++ a++ a {
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			} {
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			} for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				} int b=1; int b=1; b 1 b<=W b W b++ b++ b {
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				} {
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				} if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					} (a%2==1&&b%2==1)||(a%2==0&&b%2==0) (a%2==1&&b%2==1) a%2==1 a%2 a 2 1 b%2==1 b%2 b 2 1 (a%2==0&&b%2==0) a%2==0 a%2 a 2 0 b%2==0 b%2 b 2 0 {
						sb.append("#");
					} sb.append("#") sb.append sb "#" if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					} (a%2==0&&b%2==1)||(a%2==1&&b%2==0) (a%2==0&&b%2==1) a%2==0 a%2 a 2 0 b%2==1 b%2 b 2 1 (a%2==1&&b%2==0) a%2==1 a%2 a 2 1 b%2==0 b%2 b 2 0 {
						sb.append(".");
					} sb.append(".") sb.append sb "." sb.append("\n") sb.append sb "\n" sb.append("\n") sb.append sb "\n" H=sc.nextInt() H sc.nextInt() sc.nextInt sc W=sc.nextInt() W sc.nextInt() sc.nextInt sc System.out.print(sb) System.out.print System.out System System.out sb String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		}
} public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		}
} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		StringBuilder sb=new StringBuilder("");
		int H=sc.nextInt(),W=sc.nextInt();
		while (H!=0||W!=0){
			for(int a=1;a<=H;a++){
				for (int b=1;b<=W;b++){
					if((a%2==1&&b%2==1)||(a%2==0&&b%2==0)){
						sb.append("#");
					}else if((a%2==0&&b%2==1)||(a%2==1&&b%2==0)){
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
			H=sc.nextInt();W=sc.nextInt();
		}
		System.out.print(sb);
		}
}