import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	} main {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) scan.useDelimiter("\\s") scan.useDelimiter scan "\\s" int i = 0; i 0 while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		} i == 0 i 0 { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		} int h = scan.nextInt(); h scan.nextInt() scan.nextInt scan int w = scan.nextInt(); w scan.nextInt() scan.nextInt scan if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			} h == 0 && w == 0 h == 0 h 0 w == 0 w 0 {  //h w???0?????¨????????????
				break;
			} break; if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			} h > 0 h 0 {  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			} for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				} int j = 0; int j = 0; j 0 j < h j h j++ j++ j { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				} { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				} for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					} int k = 0; int k = 0; k 0 k < w k w k++ k++ k { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					} { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					} if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							} j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1 j%2 == 0 && k%2 == 1 j%2 == 0 j%2 j 2 0 k%2 == 1 k%2 k 2 1 k%2 == 0 && j%2 ==1 k%2 == 0 k%2 k 2 0 j%2 ==1 j%2 j 2 1 {
							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 "#" System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out String[] args args public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	}
} public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("\\s"); //?????????????????´??????????????¨?????±???????????????\\???????????????
		int i = 0;
		while(i == 0) { //break????????????????????°????????????
			int h = scan.nextInt();//??´??°??\????????????
			int w = scan.nextInt();//??´??°??\???????¨?)
			if (h == 0 && w == 0) {  //h w???0?????¨????????????
				break;
			} else if (h > 0){  //0??§???????????£?????¨????????????
				for (int j = 0; j < h; j++) { //j???h????????§?????????????????§??????
					for (int k = 0; k < w; k++) { //k???w????????§?????????????????§??????
						if (j%2 == 0 && k%2 == 1 || k%2 == 0 && j%2 ==1){
							System.out.print(".");
						} else {
							System.out.print("#");
							}
					}
						System.out.println();//\\s??§??????
				}
					System.out.println();//\\s??§??????
			}
		}
	}
}