a-a a-b a-i aaa aab aai aak aao aap aar ab- aba abb abi abk abo abp abr ai- aia aib aii aik aio aip air aka akb aki akk ako akp akr aoa aob aoi aok aoo aop aor ap- apa apb api apk apo app apr ar- ara arb ari ark aro arp arr b-p baa bab bai bak bao bap bar bba bbb bbi bbk bbo bbp bbr bi- bia bib bii bik bio bip bir bka bkb bkk bko bkp bkr boa bob boi bok boo bop bor bpa bpb bpi bpo bpp bpr bra brb bri brk bro brp brr ia- iaa iab iai iao iap iar iba ibb ibi ibk ibo ibp ibr iia iib iii iio iip iir ika ikb iki ikk iko ikr io- ioa iob ioi ioo iop ior ipa ipb ipi ipo ipp ipr ir- ira irb iri irk iro irp irr ka- kaa kab kai kak kao kap kar kba kbb kbi kbk kbo kbp kbr kia kib kii kik kio kip kir kkb kki kkk kkp kkr koa kob koi kok koo kop kor kpa kpi kpk kpo kpp kpr kra kri krk kro krp krr o-i oaa oab oai oak oao oap oar ob- oba obb obi obk obo obp obr oia oib oii oik oio oip oir oka okb oki okk oko okp okr oo- ooa oob ooi ook ooo oop oor op- opa opb opi opk opo opp opr or- ora orb ori ork oro orp orr p-p paa pab pai pak pao pap par pba pbb pbi pbk pbo pbp pbr pia pib pii pik pio pip pir pka pkb pki pko pkp pkr poa pob poi pok poo pop por ppa ppb ppi ppk ppo ppp ppr pra prb pri prk pro prp prr ra- raa rab rai rak rao rap rar rba rbb rbi rbk rbo rbp rbr ria rib rii rik rio rip rir rkb rkk rko rkp roa rob roi rok roo rop ror rpa rpb rpi rpk rpo rpp rpr rra rrb rri rrk rrp rrr