import java.io.*;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	}
} import java.io.*; io.* java public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb; sb do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true); true {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} sb = new StringBuilder() sb new StringBuilder() String[] strs = br.readLine().split("\\s+"); strs br.readLine().split("\\s+") br.readLine().split br.readLine() br.readLine br "\\s+" int height	= Integer.parseInt(strs[0]); height Integer.parseInt(strs[0]) Integer.parseInt Integer strs[0] strs 0 int width	= Integer.parseInt(strs[1]); width Integer.parseInt(strs[1]) Integer.parseInt Integer strs[1] strs 1 if (height == 0 && width == 0) break; height == 0 && width == 0 height == 0 height 0 width == 0 width 0 break; for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			} int i = 0; int i = 0; i 0 i < height i height i++ i++ i {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			} {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			} for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				} int j = 0; int j = 0; j 0 j < width j width j++ j++ j {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				} {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				} sb.append( (i + j) % 2 == 0 ? "#" : ".") sb.append sb (i + j) % 2 == 0 ? "#" : "." (i + j) % 2 == 0 (i + j) % 2 (i + j) i j 2 0 "#" "." sb.append("\n") sb.append sb "\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) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	}
} public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	}
} Main
import java.io.*;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb;
		do {
			sb = new StringBuilder();
			
			String[] strs = br.readLine().split("\\s+");
			int height	= Integer.parseInt(strs[0]);
			int width	= Integer.parseInt(strs[1]);
			
			if (height == 0 && width == 0) break;
			
			for (int i = 0; i < height; i++) {
				for (int j = 0; j < width; j++) {
					sb.append( (i + j) % 2 == 0 ? "#" : ".");
				}
				sb.append("\n");
			}
			
			System.out.println(sb);
		} while (true);
	}
}