sub sortQ2
{
	my ($s, $e, $dst) = @_;
	my $m = $s - 1;
	
	($dst->[$_] < $dst->[$e]) && (
		++$m,
		($dst->[$m], $dst->[$_]) = ($dst->[$_], $dst->[$m]),
	) for ($s .. $e-1);
	
	++$m;
	
	($dst->[$m], $dst->[$e]) = ($dst->[$e], $dst->[$m]);
	
	sortQ2($s, $m-1, $dst) if ($s < $m - 1);
	sortQ2($m+1, $e, $dst) if ($m + 1 < $e);
}