sub top_x {
    my ($list, $x) = @_;
    $x--;
    my @top;
    $#top = $x;
    for my $item ( @$list ) {
        next if defined $top[ -1 ] && $item <= $top[ -1 ];
        for my $id ( 0 .. $#top ) {
            $top[ $id ] = $item and last if ! defined $top[ $id ];
            if ( $item > $top[ $id ] ) {
                @top[ $id .. $#top ] = ($item, @top[ $id .. $#top - 1]);
                #splice(@top, $id, 0, $item), pop @top;
                last;
            }
        }
    }
    return @top;
}