a-a a-b aaa aab aan aao aar aau ab- aba abb abn abo abr abu an- ana anb ann ano anr anu aoa aob aon aoo aor aou ar- ara arb arn aro arr aru au- aua aub aun auo aur b-u baa bab ban bao bar bau bba bbb bbn bbo bbr bbu bna bnb bnn bno bnr bnu boa bob bon boo bor bou bra brb brn bro brr bru bua bub bun buo bur buu naa nab nan nao nar nau nba nbb nbn nbo nbr nbu nna nnb nnn nno nnu no- noa nob non noo nor nou nra nrb nrn nro nrr nru nua nub nun nuo nur nuu oaa oab oan oao oar oau ob- oba obb obn obo obr obu on- ona onb onn ono onr onu oo- ooa oob oon ooo oor or- ora orb orn oro orr oru ou- oua oun ouo our ra- raa rab ran rao rar rau rba rbb rbn rbo rbr rbu rna rnb rnn rno rnr rnu roa rob ron roo ror rou rra rrb rrn rrr rru rua rub run ruo rur ruu ua- uaa uab uan uao uar uau uba ubb ubn ubo ubr ubu un- una unb unn uno unr unu uoa uob uon uoo uor ur- ura urb urn uro urr uru uua uun uur uuu