a-a a-b aaa aab aan aao aau ab- aba abb abn abo abu an- ana anb ann ano anu aoa aob aon aoo aou au- aua aub aun auo b-u baa bab ban bao bau bba bbb bbn bbo bbu bna bnb bnn bno bnu boa bob bon boo bou bua bub bun buo buu naa nab nan nao nau nba nbb nbn nbo nbu nna nnb nnn nno nnu no- noa nob non noo nou nua nub nun nuo nuu oaa oab oan oao oau ob- oba obb obn obo obu on- ona onb onn ono onu oo- ooa oob oon ooo ou- oua oun ouo ua- uaa uab uan uao uau uba ubb ubn ubo ubu un- una unb unn uno unu uoa uob uon uoo uua uun uuu