a-a a-b aaa aab aak aan aao aar aau ab- aba abb abk abn abo abr abu aka akb akk akn ako akr aku an- ana anb ank ann ano anr anu aoa aob aok aon aoo aor aou ar- ara arb ark arn aro arr aru au- aua aub auk aun auo aur b-u baa bab bak ban bao bar bau bba bbb bbk bbn bbo bbr bbu bka bkb bkk bkn bko bkr bna bnb bnk bnn bno bnr bnu boa bob bok bon boo bor bou bra brb brk brn bro brr bru bua bub buk bun buo bur buu ka- kaa kab kak kan kao kar kau kba kbb kbk kbn kbo kbr kbu kkb kkk kkn kkr kku kn- kna knk knn kno knr knu koa kob kok kon koo kor kou kra krk krn kro krr kru kub kuk kun kur kuu naa nab nak nan nao nar nau nba nbb nbk nbn nbo nbr nbu nka nkk nkn nko nkr nku nna nnb nnk nnn nno nnu no- noa nob nok non noo nor nou nra nrb nrk nrn nro nrr nru nua nub nuk nun nuo nur nuu oaa oab oak oan oao oar oau ob- oba obb obk obn obo obr obu oka okb okk oko okr oku on- ona onb onk onn ono onr onu oo- ooa oob ook oon ooo oor or- ora orb ork orn oro orr oru ou- oua ouk oun ouo our ra- raa rab rak ran rao rar rau rba rbb rbk rbn rbo rbr rbu rkb rkk rko rku rna rnb rnn rno rnr rnu roa rob rok ron roo ror rou rra rrb rrk rrn rrr rru rua rub ruk run ruo rur ruu ua- uaa uab uak uan uao uar uau uba ubb ubk ubn ubo ubr ubu uka ukb ukk ukn ukr uku un- una unb unk unn uno unr unu uoa uob uok uon uoo uor ur- ura urb urk urn uro urr uru uua uun uur uuu