a-a a-b a-i aaa aab aai aak aao aap ab- aba abb abi abk abo abp ai- aia aib aii aik aio aip aka akb aki akk ako akp aoa aob aoi aok aoo aop ap- apa apb api apk apo app b-p baa bab bai bak bao bap bba bbb bbi bbk bbo bbp bi- bia bib bii bik bio bip bka bkb bkk bko bkp boa bob boi bok boo bop bpa bpb bpi bpo bpp ia- iaa iab iai iao iap iba ibb ibi ibk ibo ibp iia iib iii iio iip ika ikb iki ikk iko io- ioa iob ioi ioo iop ipa ipb ipi ipo ipp ka- kaa kab kai kak kao kap kba kbb kbi kbk kbo kbp kia kib kii kik kio kip kkb kki kkk kkp koa kob koi kok koo kop kpa kpi kpk kpo kpp o-i oaa oab oai oak oao oap ob- oba obb obi obk obo obp oia oib oii oik oio oip oka okb oki okk oko okp oo- ooa oob ooi ook ooo oop op- opa opb opi opk opo opp p-p paa pab pai pak pao pap pba pbb pbi pbk pbo pbp pia pib pii pik pio pip pka pkb pki pko pkp poa pob poi pok poo pop ppa ppb ppi ppk ppo ppp