a-a a-b aaa aab aah aao aav ab- aba abb abh abo abv aha ahb ahh aho ahv aoa aob aoh aoo aov av- ava avb avh avo baa bab bah bao bav bba bbb bbh bbo bha bhb bhh bho bhv boa bob boh boo bov bva bvb bvh bvo bvv haa hab hah hao hav hba hbb hbh hbo hbv hha hhb hhh hho hhv hoa hob hoh hoo hov hv- hva hvb hvo hvv oaa oab oah oao oav ob- oba obb obh obo obv oha ohh oho oo- ooa oob ooh ooo oov ov- ova ovb ovh ovo ovv v-a vaa vab vah vao vav vba vbh vbo vbv vh- vha vhb vho voa vob voh voo vov vva vvb vvo vvv