import java.util.Scanner;
class Main
{
	public static void main(String[] args)throws Exception
	{
		Scanner scan=new Scanner(System.in);
		
		while(true)
		{
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		}
		
	}

} import java.util.Scanner; Scanner java.util class Main
{
	public static void main(String[] args)throws Exception
	{
		Scanner scan=new Scanner(System.in);
		
		while(true)
		{
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		}
		
	}

} Main public static void main(String[] args)throws Exception
	{
		Scanner scan=new Scanner(System.in);
		
		while(true)
		{
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		}
		
	} main {
		Scanner scan=new Scanner(System.in);
		
		while(true)
		{
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		}
		
	} Scanner scan=new Scanner(System.in); scan new Scanner(System.in) while(true)
		{
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		} true {
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		} double H=scan.nextDouble(); H scan.nextDouble() scan.nextDouble scan double W=scan.nextDouble(); W scan.nextDouble() scan.nextDouble scan if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			} H==0&&W==0 H==0 H 0 W==0 W 0 {
				break;				
			} break; {
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			} for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				} double i=1; double i=1; i 1 i<=H i H i++ i++ i {	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				} {	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				} if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					} i%2==1 i%2 i 2 1 {
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					} for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						} double a=1; double a=1; a 1 a<=W a W a++ a++ a {
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						} {
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						} if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							} a%2==1 a%2 a 2 1 {
								System.out.print("#");
							} System.out.print("#") System.out.print System.out System System.out "#" if(a%2==0)
							{
								System.out.print(".");
							} a%2==0 a%2 a 2 0 {
								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 "" if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					} i%2==0 i%2 i 2 0 {
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					} for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						} double b=1; double b=1; b 1 b<=W b W b++ b++ b {
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						} {
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						} if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							} b%2==1 b%2 b 2 1 {
								System.out.print(".");
							} System.out.print(".") System.out.print System.out System System.out "." if(b%2==0)
							{
								System.out.print("#");
							} b%2==0 b%2 b 2 0 {
								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.print("\n") System.out.print System.out System System.out "\n" String[] args args
import java.util.Scanner;
class Main
{
	public static void main(String[] args)throws Exception
	{
		Scanner scan=new Scanner(System.in);
		
		while(true)
		{
			double H=scan.nextDouble();		
			double W=scan.nextDouble();

			if(H==0&&W==0)
			{
				break;				
			}
			else
			{
				for(double i=1;i<=H;i++)
				{	
					if(i%2==1)
					{
						for(double a=1;a<=W;a++)
						{
							if(a%2==1)
							{
								System.out.print("#");
							}
							else if(a%2==0)
							{
								System.out.print(".");
							}
						}
						System.out.println("");
					}
					else if(i%2==0)
					{
						for(double b=1;b<=W;b++)
						{
							if(b%2==1)
							{
								System.out.print(".");
							}
							else if(b%2==0)
							{
								System.out.print("#");
							}
						}
						System.out.println("");
					
					}
				}System.out.print("\n");
			
			}
			
		}
		
	}

}