a-a a-c aaa aac aak aao aas ac- aca acc ack aco acs aka akc akk ako aks aoa aoc aok aoo aos as- asa asc ask aso ass c-- caa cac cak cao cas cca ccc cck cco ccs cka ckc cko cks co- coa coc cok coo cos csa csc csk cso css ka- kaa kac kak kao kas kca kcc kck kcs kkc kkk kks koa koc kok koo kos ksa ksc ksk kso kss oaa oac oak oao oas oc- oca occ ock oco ocs oka okc okk oko oks oo- ooa ooc ook ooo oos os- osa osc osk oso oss saa sac sak sao sas sca scc sck sco scs sk- ska skc skk sko sks soa soc sok soo sos ss- ssa ssc ssk sso sss