import java.util.Scanner;

class Main
{
	public static void main ( String[] args ) {
		Scanner sc = new Scanner ( System.in );
		
		int H = 0;
		int W = 0;
		boolean flg = true;

		while ( true ) {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		}
	}
} import java.util.Scanner; Scanner java.util class Main
{
	public static void main ( String[] args ) {
		Scanner sc = new Scanner ( System.in );
		
		int H = 0;
		int W = 0;
		boolean flg = true;

		while ( true ) {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		}
	}
} Main public static void main ( String[] args ) {
		Scanner sc = new Scanner ( System.in );
		
		int H = 0;
		int W = 0;
		boolean flg = true;

		while ( true ) {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		}
	} main {
		Scanner sc = new Scanner ( System.in );
		
		int H = 0;
		int W = 0;
		boolean flg = true;

		while ( true ) {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		}
	} Scanner sc = new Scanner ( System.in ); sc new Scanner ( System.in ) int H = 0; H 0 int W = 0; W 0 boolean flg = true; flg true while ( true ) {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		} true {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		} H = sc.nextInt () H sc.nextInt () sc.nextInt sc W = sc.nextInt () W sc.nextInt () sc.nextInt sc if ( H == 0 && W == 0 ) {
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			} int i = 1; int i = 1; i 1 i <= H i H i++ i++ i {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			} {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			} if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				} i % 2 == 0 i % 2 i 2 0 {
					flg = false;
				} flg = false flg false {
					flg = true;
				} flg = true flg true for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				} int j = 1; int j = 1; j 1 j <= W j W j++ j++ j {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				} {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				} if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					} flg == true flg true {
						System.out.print ( "#" );
						flg = false;
					} System.out.print ( "#" ) System.out.print System.out System System.out "#" flg = false flg false {
						System.out.print ( "." );
						flg = true;
					} System.out.print ( "." ) System.out.print System.out System System.out "." flg = true flg true 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
import java.util.Scanner;

class Main
{
	public static void main ( String[] args ) {
		Scanner sc = new Scanner ( System.in );
		
		int H = 0;
		int W = 0;
		boolean flg = true;

		while ( true ) {
			H = sc.nextInt ();
			W = sc.nextInt ();

			if ( H == 0 && W == 0 ) {
				break;
			}
			
			for ( int i = 1; i <= H; i++ ) {
				if ( i % 2 == 0 ) {
					flg = false;
				} else {
					flg = true;
				}
				
				for ( int j = 1; j <= W; j++ ) {
					if ( flg == true ) {
						System.out.print ( "#" );
						flg = false;
					} else {
						System.out.print ( "." );
						flg = true;
					}
				}
				System.out.println ();
			}
			System.out.println ();
		}
	}
}