when i run the above code, it is showing the error-undefined variable $file1.please help me

c:\@Work\Perl\monks\Sidd@786>dir do.txt
 Volume in drive C is Acer
 Volume Serial Number is 9840-785B

 Directory of c:\@Work\Perl\monks\Sidd@786

File Not Found

c:\@Work\Perl\monks\Sidd@786>perl
#use strict;
use warnings;

$file1 = 'goodfile.txt';
$file2 = 'badfile.txt';

open $h2, '<', $file2 or die "cannot open file2";
@a2 = <$h2>;
close $h2;
chomp @a2;

$match = join '|', @a2;
$match = qr/$match/;

open $f3,'>',"do.txt" or die "$!";

open $h1, '<', $file1 or die "cannot open file1";
my @a1 = <$h1>;
close $h1;

# print grep {$_ !~ $match} @a1;
print $f3 grep {$_ !~ $match} @a1;

__END__

c:\@Work\Perl\monks\Sidd@786>cat do.txt
don't you
[download]