import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		Scanner kb = new Scanner( System.in);	
		
		while( true ) {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		}
	}
} import java.util.Scanner; Scanner java.util class Main {
	public static void main(String[] args) {
		Scanner kb = new Scanner( System.in);	
		
		while( true ) {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		}
	}
} Main public static void main(String[] args) {
		Scanner kb = new Scanner( System.in);	
		
		while( true ) {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		}
	} main {
		Scanner kb = new Scanner( System.in);	
		
		while( true ) {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		}
	} Scanner kb = new Scanner( System.in); kb new Scanner( System.in) while( true ) {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		} true {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		} int H = kb.nextInt(); H kb.nextInt() kb.nextInt kb int W = kb.nextInt(); W kb.nextInt() kb.nextInt kb if( 0==W && 0==H ) { break; } 0==W && 0==H 0==W 0 W 0==H 0 H { break; } break; boolean cPattern=true; cPattern true for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			} int i=0; int i=0; i 0 i<H i H i++ i++ i {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			} {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			} cPattern= (0==(i%2))? true: false cPattern (0==(i%2))? true: false (0==(i%2)) 0 (i%2) i 2 true false for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				} int j=0; int j=0; j 0 j<W j W j++ j++ j {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				} {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				} if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					} cPattern {
						System.out.print( "#" );
						cPattern=!cPattern;
					} System.out.print( "#" ) System.out.print System.out System System.out "#" cPattern=!cPattern cPattern !cPattern cPattern {
						System.out.print( "." );
						cPattern=!cPattern;
					} System.out.print( "." ) System.out.print System.out System System.out "." cPattern=!cPattern cPattern !cPattern cPattern System.out.print( "\n" ) System.out.print System.out System System.out "\n" 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) {
		Scanner kb = new Scanner( System.in);	
		
		while( true ) {
			int H = kb.nextInt();
			int W = kb.nextInt();
			
			if( 0==W && 0==H ) { break; }
			
			boolean cPattern=true;
			for( int i=0; i<H; i++ ) {
				cPattern= (0==(i%2))? true: false;
				for( int j=0; j<W; j++ ) {
					if( cPattern ) {
						System.out.print( "#" );
						cPattern=!cPattern;
					} else {
						System.out.print( "." );
						cPattern=!cPattern;
					}
				}
				System.out.print( "\n" );
			}
			System.out.print( "\n" );
		}
	}
}