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; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        }
    }
} 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; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        }
    }
} 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; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        }
    } main {
        Scanner kb = new Scanner( System.in);   
          
        while( true ) {
            int H = kb.nextInt();
            int W = kb.nextInt();
              
            if( 0==W && 0==H ) { break; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        }
    } 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; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        } true {
            int H = kb.nextInt();
            int W = kb.nextInt();
              
            if( 0==W && 0==H ) { break; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        } 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; StringBuilder output = new StringBuilder( 300+1 ); output new StringBuilder( 300+1 ) boolean cPattern=true; cPattern true for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            } int i=0; int i=0; i 0 i<H i H i++ i++ i {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            } {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            } cPattern= (0==(i&1))? true: false cPattern (0==(i&1))? true: false (0==(i&1)) 0 (i&1) i 1 true false for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                } int j=0; int j=0; j 0 j<W j W j++ j++ j {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                } {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                } if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    } cPattern {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } output.append( "#"  ) output.append output "#" cPattern=!cPattern cPattern !cPattern cPattern {
                        output.append( "."  );
                        cPattern=!cPattern;
                    } output.append( "."  ) output.append output "." cPattern=!cPattern cPattern !cPattern cPattern output.append( "\n"  ) output.append output "\n" System.out.println( output ) System.out.println System.out System System.out output 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; }
           
           StringBuilder output = new StringBuilder( 300+1 );	
            boolean cPattern=true;
            for( int i=0; i<H; i++ ) {
                cPattern= (0==(i&1))? true: false;
                for( int j=0; j<W; j++ ) {
                    if( cPattern ) {
                    	output.append( "#"  );
                        cPattern=!cPattern;
                    } else {
                        output.append( "."  );
                        cPattern=!cPattern;
                    }
                }
                output.append( "\n"  );
            }
            System.out.println( output );
        }
    }
}