
import java.util.Scanner;


public class Main {
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} Main public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} main {
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} ; {
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} {
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} int w = scanner.nextInt(); w scanner.nextInt() scanner.nextInt scanner int h = scanner.nextInt(); h scanner.nextInt() scanner.nextInt scanner if(w==0 && h==0)
			{
				break;
			} w==0 && h==0 w==0 w 0 h==0 h 0 {
				break;
			} break; for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			} int i=0; int i=0; i 0 i<w i w i++ i++ i {
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			} {
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			} for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				} int j=0; int j=0; j 0 j<h j h j++ j++ j {
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				} {
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				} if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					} (i%2==0 && j%2==0) || (i%2==1 && j%2==1) (i%2==0 && j%2==0) i%2==0 i%2 i 2 0 j%2==0 j%2 j 2 0 (i%2==1 && j%2==1) i%2==1 i%2 i 2 1 j%2==1 j%2 j 2 1 {
						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.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)
	{
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} public class Main {
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} Main

import java.util.Scanner;


public class Main {
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		for(;;)
		{
			int w = scanner.nextInt();
			int h = scanner.nextInt();
			
			if(w==0 && h==0)
			{
				break;
			}
			
			for(int i=0; i<w; i++)
			{
				for(int j=0; j<h; j++)
				{
					if((i%2==0 && j%2==0) || (i%2==1 && j%2==1))
					{
						System.out.print("#");
					}
					else
					{
						System.out.print(".");
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
}