import java.util.Scanner;

public class Main{

	public static void main(String[] args) {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	}
} import java.util.Scanner; Scanner java.util public class Main{

	public static void main(String[] args) {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	}
} Main public static void main(String[] args) {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	} main {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	} int g g r; r Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		} true {
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		} boolean bool=false; bool false g = scan.nextInt() g scan.nextInt() scan.nextInt scan r = scan.nextInt() r scan.nextInt() scan.nextInt scan if( (g|r) == 0) break; (g|r) == 0 (g|r) g r 0 break; for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			} int i=0; int i=0; i 0 i<g i g i++ i++ i {
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			} {
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			} for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				} int j=0; int j=0; j 0 j<r j r j++ j++ j {
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				} {
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				} if(!bool) System.out.print("#");
					else System.out.print("."); !bool bool System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." bool = !bool bool !bool bool System.out.println() System.out.println System.out System System.out if(r%2 == 0) bool = !bool; r%2 == 0 r%2 r 2 0 bool = !bool bool !bool bool System.out.println() System.out.println System.out System System.out scan.close() scan.close scan String[] args args public class Main{

	public static void main(String[] args) {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	}
} public class Main{

	public static void main(String[] args) {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	}
} Main
import java.util.Scanner;

public class Main{

	public static void main(String[] args) {

		int g,r;

		Scanner scan = new Scanner(System.in);

		while(true)
		{
			boolean bool=false;

			g = scan.nextInt();
			r = scan.nextInt();

			if( (g|r) == 0) break;

			for(int i=0; i<g; i++)
			{
				for(int j=0; j<r; j++)
				{
					if(!bool) System.out.print("#");
					else System.out.print(".");

					bool = !bool;
				}

				System.out.println();

				if(r%2 == 0) bool = !bool;
			}

			System.out.println();

		}

		scan.close();

	}
}