a-a a-c aaa aac aak aao aar ac- aca acc ack aco acr aka akc akk ako akr aoa aoc aok aoo aor ar- ara arc ark aro arr c-- caa cac cak cao car cca ccc cck cco ccr cka ckc cko co- coa coc cok coo cor cra crc crk cro crr ka- kaa kac kak kao kar kca kcc kck kcr kkc kkk kkr koa koc kok koo kor kra krc krk kro krr oaa oac oak oao oar oc- oca occ ock oco ocr oka okc okk oko okr oo- ooa ooc ook ooo oor or- ora orc ork oro orr ra- raa rac rak rao rar rca rcc rco rcr rkc rkk rko roa roc rok roo ror rra rrc rrk rrr