-ic a-a a-b a-c a-i aaa aab aac aai aak aao aar ab- aba abb abc abi abk abo abr ac- aca acb acc aci ack aco acr ai- aia aib aic aii aik aio air aka akb akc aki akk ako akr aoa aob aoc aoi aok aoo aor ar- ara arb arc ari ark aro arr baa bab bac bai bak bao bar bba bbb bbc bbi bbk bbo bbr bca bcb bcc bci bck bco bcr bi- bia bib bic bii bik bio bir bka bkb bkc bkk bko bkr boa bob boc boi bok boo bor bra brb bri brk bro brr c-- caa cab cac cai cak cao car cba cbb cbc cbi cbk cbo cbr cca ccb ccc cci cck cco ccr ci- cia cib cic cii cik cio cir cka ckb ckc cki cko co- coa cob coc coi cok coo cor cra crb crc cri crk cro crr ia- iaa iab iac iai iao iar iba ibb ibc ibi ibk ibo ibr ica icb icc ici ick ico icr iia iib iic iii iio iir ika ikb ikc iki ikk iko ikr io- ioa iob ioc ioi ioo ior ir- ira irb irc iri irk iro irr ka- kaa kab kac kai kak kao kar kba kbb kbc kbi kbk kbo kbr kca kcb kcc kci kck kcr kia kib kic kii kik kio kir kkb kkc kki kkk kkr koa kob koc koi kok koo kor kra krc kri krk kro krr o-i oaa oab oac oai oak oao oar ob- oba obb obc obi obk obo obr oc- oca ocb occ oci ock oco ocr oia oib oic oii oik oio oir oka okb okc oki okk oko okr oo- ooa oob ooc ooi ook ooo oor or- ora orb orc ori ork oro orr ra- raa rab rac rai rak rao rar rba rbb rbc rbi rbk rbo rbr rca rcb rcc rci rco rcr ria rib ric rii rik rio rir rkb rkc rkk rko roa rob roc roi rok roo ror rra rrb rrc rri rrk rrr