a-a a-c aaa aac aak aan aao aar ac- aca acc ack acn aco acr aka akc akk akn ako akr an- ana anc ank ann ano anr aoa aoc aok aon aoo aor ar- ara arc ark arn aro arr c-- caa cac cak can cao car cca ccc cck ccn cco ccr cka ckc cko cn- cna cnc cnn cno cnr co- coa coc cok con coo cor cra crc crk crn cro crr ka- kaa kac kak kan kao kar kca kcc kck kcn kcr kkc kkk kkn kkr kn- kna knc knk knn kno knr koa koc kok kon koo kor kra krc krk krn kro krr naa nac nak nan nao nar nca ncc nck ncn nco ncr nka nkc nkk nkn nko nkr nna nnc nnk nnn nno no- noa noc nok non noo nor nra nrc nrk nrn nro nrr oaa oac oak oan oao oar oc- oca occ ock ocn oco ocr oka okc okk oko okr on- ona onc onk onn ono onr oo- ooa ooc ook oon ooo oor or- ora orc ork orn oro orr ra- raa rac rak ran rao rar rca rcc rcn rco rcr rkc rkk rko rna rnc rnn rno rnr roa roc rok ron roo ror rra rrc rrk rrn rrr