a-a a-c aaa aac aae aak aao aas ac- aca acc ace ack aco acs aea aec aee aek aeo aes aka akc ake akk ako aks aoa aoc aoe aok aoo aos as- asa asc ase ask aso ass c-- caa cac cae cak cao cas cca ccc cce cck cco ccs ce- cea cec cee cek ceo ces cka ckc cko cks co- coa coc coe cok coo cos csa csc cse csk cso css eaa eac eae eak eao eas ec- eca ecc ece eck eco ecs eea eec eee eek eeo ees eka ekc eke eko eks eo- eoa eoc eoe eok eoo eos es- esa esc ese esk eso ess ka- kaa kac kae kak kao kas kca kcc kce kck kcs ke- kea kec kee kek keo kes kkc kke kkk kks koa koc koe kok koo kos ksa ksc kse ksk kso kss oaa oac oae oak oao oas oc- oca occ ock oco ocs oea oec oee oeo oes oka okc oke okk oko oks oo- ooa ooc ook ooo oos os- osa osc ose osk oso oss saa sac sae sak sao sas sca scc sce sck sco scs se- sea sec see sek seo ses sk- ska skc ske skk sko sks soa soc soe sok soo sos ss- ssa ssc sse ssk sso sss