my $dropdown = CGI::param('one');
[...]
my $size = length($dropdown);
if($size > 50){
              exit;
              }

$dropdown =~ s/;//g;
$dropdown =~ s/<//g;
$dropdown =~ s/>//g;
$dropdown =~ s/\*//g;
$dropdown =~ s/|//g;
$dropdown =~ s/\[//g;
$dropdown =~ s/\]//g;
$dropdown =~ s/{//g;
$dropdown =~ s/}//g;
$dropdown =~ s/@//g;
$dropdown =~ s/&//g;
$dropdown =~ s/\\//g;