a-a aaa aaf aak aao aar aav af- afa aff afk afo afr afv aka akk ako akr akv aoa aof aok aoo aor aov ar- ara arf ark aro arr arv av- ava avf avk avo avr faa faf fak fao far fav ffa fff ffk ffo ffr ffv fka fkf fkk foa fof fok foo for fra frf frk fro frr fva fvk ka- kaa kaf kak kao kar kav kfa kff kfo kkk kkr kkv koa kof kok koo kor kra krf krk kro krr krv kva kvk kvo kvr kvv oaa oaf oak oao oar oav of- ofa off ofo ofr ofv oka okk oko okr oo- ooa oof ook ooo oor oov or- ora orf ork oro orr orv ov- ova ovf ovo ovv ra- raa raf rak rao rar rav rfa rff rfk rfo rfr rfv rkf rkk rko rkv roa rof rok roo ror rov rra rrf rrk rrr rva rvf rvo rvr rvv v-a vaa vak vao var vav vfa vff vfr vfv vka voa vof vok voo vor vov vra vrf vrk vrr vva vvo vvr vvv