-ic a-a a-b a-c a-i aaa aab aac aai aak aao ab- aba abb abc abi abk abo ac- aca acb acc aci ack aco ai- aia aib aic aii aik aio aka akb akc aki akk ako aoa aob aoc aoi aok aoo baa bab bac bai bak bao bba bbb bbc bbi bbk bbo bca bcb bcc bci bck bco bi- bia bib bic bii bik bio bka bkb bkc bkk bko boa bob boc boi bok boo c-- caa cab cac cai cak cao cba cbb cbc cbi cbk cbo cca ccb ccc cci cck cco ci- cia cib cic cii cik cio cka ckb ckc cki cko co- coa cob coc coi cok coo ia- iaa iab iac iai iao iba ibb ibc ibi ibk ibo ica icb icc ici ick ico iia iib iic iii iio ika ikb ikc iki ikk iko io- ioa iob ioc ioi ioo ka- kaa kab kac kai kak kao kba kbb kbc kbi kbk kbo kca kcb kcc kci kck kia kib kic kii kik kio kkb kkc kki kkk koa kob koc koi kok koo o-i oaa oab oac oai oak oao ob- oba obb obc obi obk obo oc- oca ocb occ oci ock oco oia oib oic oii oik oio oka okb okc oki okk oko oo- ooa oob ooc ooi ook ooo