import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.StringTokenizer; StringTokenizer java.util public class Main {
	public static void main(String[] args) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}
} Main public static void main(String[] args) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	} main {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	} try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		} catch (IOException e) {
			System.err.println(e);
		} IOException e {
			System.err.println(e);
		} System.err.println(e) System.err.println System.err System System.err e {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} InputStreamReader isr = new InputStreamReader(System.in); isr new InputStreamReader(System.in) BufferedReader br = new BufferedReader(isr); br new BufferedReader(isr) while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			} true {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			} String buf = br.readLine(); buf br.readLine() br.readLine br StringTokenizer st = new StringTokenizer(buf, " "); st new StringTokenizer(buf, " ") int H = Integer.parseInt(st.nextToken()); H Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st int W = Integer.parseInt(st.nextToken()); W Integer.parseInt(st.nextToken()) Integer.parseInt Integer st.nextToken() st.nextToken st if (W == 0 && H == 0)
					break; W == 0 && H == 0 W == 0 W 0 H == 0 H 0 break; if (H >= 300 && W >= 300)
					break; H >= 300 && W >= 300 H >= 300 H 300 W >= 300 W 300 break; for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				} int i = 1; int i = 1; i 1 i <= H i H i++ i++ i {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				} {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				} for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					} int j = 1; int j = 1; j 1 j <= W j W j++ j++ j {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					} {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					} if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						} i%2==0 i%2 i 2 0 {
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						} if (j%2==0)
								System.out.print("#");
							else
								System.out.print("."); j%2==0 j%2 j 2 0 System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						} if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#"); j%2==0 j%2 j 2 0 System.out.print(".") System.out.print System.out System System.out "." 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) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}
} public class Main {
	public static void main(String[] args) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}
}