a-a a-b a-c aaa aab aac aah aao aau ab- aba abb abc abh abo abu ac- aca acb acc ach aco acu aha ahb ahc ahh aho ahu aoa aob aoc aoh aoo aou au- aua aub auc auh auo b-u baa bab bac bah bao bau bba bbb bbc bbh bbo bbu bca bcb bcc bch bco bcu bha bhb bhc bhh bho bhu boa bob boc boh boo bou bua bub buc buh buo buu c-- caa cab cac cah cao cau cba cbb cbc cbh cbo cbu cca ccb ccc cch cco ccu ch- cha chb chc chh cho chu co- coa cob coc coh coo cou cua cub cuc cuh cuo cuu haa hab hac hah hao hau hba hbb hbc hbh hbo hbu hca hcb hcc hch hco hha hhb hhc hhh hho hhu hoa hob hoc hoh hoo hou hua hub huc huh huo huu oaa oab oac oah oao oau ob- oba obb obc obh obo obu oc- oca ocb occ och oco ocu oha ohc ohh oho ohu oo- ooa oob ooc ooh ooo ou- oua ouc ouh ouo ua- uaa uab uac uah uao uau uba ubb ubc ubh ubo ubu uca ucb ucc uch uco ucu uha uhb uhc uhh uho uhu uoa uob uoc uoo uua uuc uuu