a-a a-b aaa aab aad aan aar aau ab- aba abb abd abn abr abu ad- ada adb add adn adr adu an- ana anb and ann anr anu ar- ara arb ard arn arr aru au- aua aub aud aun aur b-u baa bab bad ban bar bau bba bbb bbd bbn bbr bbu bda bdb bdd bdr bdu bna bnb bnd bnn bnr bnu bra brb brd brn brr bru bua bub bud bun bur buu daa dab dad dan dar dau dba dbb dbd dbn dbr dbu dda ddb ddd ddn ddr ddu dna dnb dnd dnn dnr dra drb drd drn drr dru dua dub dud dun dur naa nab nad nan nar nau nba nbb nbd nbn nbr nbu nda ndb ndd ndn ndr ndu nna nnb nnn nnu nra nrb nrd nrn nrr nru nua nub nud nun nur nuu ra- raa rab rad ran rar rau rba rbb rbd rbn rbr rbu rda rdb rdd rdn rdr rdu rna rnb rnd rnn rnr rnu rra rrb rrd rrn rrr rru rua rub rud run rur ruu ua- uaa uab uad uan uar uau uba ubb ubn ubr ubu uda udb udd udn udr udu un- una unb und unn unr unu ur- ura urb urd urn urr uru uua uun uur uuu