use strict;
use warnings;
my $passwdfile = "d.txt";
my %seen = ();
{
   local @ARGV = ($passwdfile);
   local $^I = '.bac'; 
   while(<>){
   	  $_ =~ s/^\s+//;
      $seen{$_}++;
      next if $seen{$_} > 1;
      print;
   }
}
print "finished";
##</code><code>##

5
5
5 

5

5

6


55

6
66

5
5
5 

5
 
##</code><code>##

5
5 
6
55
66