sub beautify
{
    my %stuff;
    @stuff{@_} = undef;
    return sort keys %stuff;
}

##</code><code>##

print join ' ',beautify(qw(h e l l o w o r l d)); # prints "d e h l o r w"
print join ' ',beautify(qw(b u m b l e b e e));   # prints "b e l m u"

##</code><code>##

sub beautify
{
    my %stuff;
    $stuff{$_}++ for(@_);
    return sort { $stuff{$a} <=> $stuff{$b} } keys %stuff;
}

##</code><code>##

print join ' ',beautify(qw(h e l l o w o r l d)); # prints "e w r h d o l"
print join ' ',beautify(qw(b u m b l e b e e));   # prints "m u l e b"