import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	}

	public static void even( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	}
	
	public static void odd( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	}
	
	
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	}

	public static void even( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	}
	
	public static void odd( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	}
	
	
} Main public static void main(String[] args) {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	} main {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	} Scanner sc = new Scanner( System.in ); sc new Scanner( System.in ) while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		} true {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		} int height	= sc.nextInt(); height sc.nextInt() sc.nextInt sc int width	= sc.nextInt(); width sc.nextInt() sc.nextInt sc if ( height	== 0 &&	width	== 0 ) break; height	== 0 &&	width	== 0 height	== 0 height 0 width	== 0 width 0 break; for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			} int i = 0; int i = 0; i 0 i < height i height i++ i++ i {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			} {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			} if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				} ( i % 2 ) == 0 ( i % 2 ) i 2 0 {
					even( width );
					
				} even( width ) even width {
					odd( width );
					
				} odd( width ) odd width System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args public static void even( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	} even {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	} for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		} int i = 0; int i = 0; i 0 i < width i width i++ i++ i {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		} {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		} if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			} ( i % 2 ) == 0 ( i % 2 ) i 2 0 {
				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" int width width public static void odd( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	} odd {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	} for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		} int i = 0; int i = 0; i 0 i < width i width i++ i++ i {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		} {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		} if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			} ( i % 2 ) == 0 ( i % 2 ) i 2 0 {
				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" int width width public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	}

	public static void even( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	}
	
	public static void odd( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	}
	
	
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	}

	public static void even( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	}
	
	public static void odd( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	}
	
	
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner( System.in );
		
		while( true ) {
			int height	= sc.nextInt();
			int width	= sc.nextInt();
			
			if ( height	== 0 &&	width	== 0 ) break;
			
			for (int i = 0; i < height; i++ ) {
				if( ( i % 2 ) == 0 ) {
					even( width );
					
				} else {
					odd( width );
					
				}
				
			}
			
			System.out.print("\n");
			
		}
	}

	public static void even( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print("#");

			} else {
				System.out.print(".");
				
			}

		}
		
		System.out.print("\n");

	}
	
	public static void odd( int width ) {
		for (int i = 0; i < width; i++ ) {
			if( ( i % 2 ) == 0 ) {
				System.out.print(".");

			} else {
				System.out.print("#");
				
			}

		}
		
		System.out.print("\n");
	}
	
	
}