import java.io.*;

public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
} import java.io.*; io.* java public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		} true {
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		} String line = br.readLine(); line br.readLine() br.readLine br String[] str = line.split(" "); str line.split(" ") line.split line " " int h = Integer.parseInt(str[0]); h Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int w = Integer.parseInt(str[1]); w Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			} h == 0 && w == 0 h == 0 h 0 w == 0 w 0 { //??\????????¨??????0
				break;
			} break; for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			} int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			} {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			} for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 } int k = 0; int k = 0; k 0 k < w k w k++ k++ k {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 } {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 } if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	} (i%2) == (k%2) (i%2) i 2 (k%2) k 2 {
						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.print("\n") System.out.print System.out System System.out "\n" System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
} public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
} Main
import java.io.*;

public class Main{
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = br.readLine();
			String[] str = line.split(" ");
			int h = Integer.parseInt(str[0]);
			int w = Integer.parseInt(str[1]);
			if ( h == 0 && w == 0 ){ //??\????????¨??????0
				break;
			}

			for (int i = 0; i < h ; i++ ) {
				for (int k = 0; k < w ; k++ ) {
					if ((i%2) == (k%2)) {
						System.out.print("#");
					}else{
						System.out.print(".");
				 	}
				 }
					System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
}