a-a a-b aaa aab aak aan aar aau ab- aba abb abk abn abr abu aka akb akk akn akr aku an- ana anb ank ann anr anu ar- ara arb ark arn arr aru au- aua aub auk aun aur b-u baa bab bak ban bar bau bba bbb bbk bbn bbr bbu bka bkb bkk bkn bkr bna bnb bnk bnn bnr bnu bra brb brk brn brr bru bua bub buk bun bur buu ka- kaa kab kak kan kar kau kba kbb kbk kbn kbr kbu kkb kkk kkn kkr kku kn- kna knk knn knr knu kra krk krn krr kru kub kuk kun kur kuu naa nab nak nan nar nau nba nbb nbk nbn nbr nbu nka nkk nkn nkr nku nna nnb nnk nnn nnu nra nrb nrk nrn nrr nru nua nub nuk nun nur nuu ra- raa rab rak ran rar rau rba rbb rbk rbn rbr rbu rkb rkk rku rna rnb rnn rnr rnu rra rrb rrk rrn rrr rru rua rub ruk run rur ruu ua- uaa uab uak uan uar uau uba ubb ubk ubn ubr ubu uka ukb ukk ukn ukr uku un- una unb unk unn unr unu ur- ura urb urk urn urr uru uua uun uur uuu