Main();

Main
{
   my %dtree = init();
   processDtree(\%dtree);
}

sub processDtree
{
   my $rh_dtree = shift;
   
   foreach my $parent ( keys %{$rh_dtree} )
   {
      my @nodenames = ();
      hash_walk( \%{$rh_dtree->{$parent}},[],\@nodenames);
      print join("\n",@nodenames) . "\n";
exit;
   }
}

sub hash_walk
{
    my ($rh_dtree,$ra_keys,$ra_nodenames) = @_;
    
    while (my ($k, $v) = each %$rh_dtree) 
    {
       # keep keys ordered.
       push(@$ra_keys,$k);
       if ( scalar keys %{$v} ) 
       {
          hash_walk($v,$ra_keys,$ra_nodenames);
       }
    }
    push(@$ra_nodenames, join(".",@$ra_keys));
    @$ra_keys = ();
    
}