my $text="qwertyuiopasdfghjklzxcvbnm";

my @ltrs=split //,$text;

my ($val,@set,@unset)=(1);

while ($val) {
	push @{(ord($_) & $val) ? \@set : \@unset}, $_
		foreach @ltrs;
	$val <<= 1;
	@ltrs=( splice( @unset, 0, @unset ), splice( @set, 0, @set ) );
}

print join("-",@ltrs)."\n"