import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Main {
	public static void main(String[] args) throws IOException{
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
	public static void main(String[] args) throws IOException{
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	}
} Main public static void main(String[] args) throws IOException{
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	} main {
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	} int h h w; w String[] str; str BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder builder = new StringBuilder(); builder new StringBuilder() while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		} true {
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		} str = br.readLine().split(" ") str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " h = Integer.parseInt(str[0]) h Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 w = Integer.parseInt(str[1]) w Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 if(h==0 && w==0)break; h==0 && w==0 h==0 h 0 w==0 w 0 break; for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			} int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			} {
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			} for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				} int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				} {
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				} if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					} (i+j)%2 == 0 (i+j)%2 (i+j) i j 2 0 {
						builder.append("#");
					} builder.append("#") builder.append builder "#" {
						builder.append(".");
					} builder.append(".") builder.append builder "." builder.append("\n") builder.append builder "\n" builder.append("\n") builder.append builder "\n" builder.delete(builder.length() - 1, builder.length()) builder.delete builder builder.length() - 1 builder.length() builder.length builder 1 builder.length() builder.length builder System.out.println(builder) System.out.println System.out System System.out builder br.close() br.close br String[] args args public class Main {
	public static void main(String[] args) throws IOException{
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	}
} public class Main {
	public static void main(String[] args) throws IOException{
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Main {
	public static void main(String[] args) throws IOException{
		int h,w;
		String[] str;

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();

		while(true){
			str = br.readLine().split(" ");
			h = Integer.parseInt(str[0]);
			w = Integer.parseInt(str[1]);

			if(h==0 && w==0)break;

			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if((i+j)%2 == 0){
						builder.append("#");
					}else{
						builder.append(".");
					}
				}
				builder.append("\n");
			}
			builder.append("\n");
		}

		builder.delete(builder.length() - 1, builder.length());
		System.out.println(builder);
		br.close();
	}
}