a-a a-c aaa aac aak aan aao ac- aca acc ack acn aco aka akc akk akn ako an- ana anc ank ann ano aoa aoc aok aon aoo c-- caa cac cak can cao cca ccc cck ccn cco cka ckc cko cn- cna cnc cnn cno co- coa coc cok con coo ka- kaa kac kak kan kao kca kcc kck kcn kkc kkk kkn kn- kna knc knk knn kno koa koc kok kon koo naa nac nak nan nao nca ncc nck ncn nco nka nkc nkk nkn nko nna nnc nnk nnn nno no- noa noc nok non noo oaa oac oak oan oao oc- oca occ ock ocn oco oka okc okk oko on- ona onc onk onn ono oo- ooa ooc ook oon ooo