a-a a-c aaa aac aae aak aas ac- aca acc ace ack acs aea aec aee aek aes aka akc ake akk aks as- asa asc ase ask ass c-- caa cac cae cak cas cca ccc cce cck ccs ce- cea cec cee cek ces cka ckc cks csa csc cse csk css eaa eac eae eak eas ec- eca ecc ece eck ecs eea eec eee eek ees eka ekc eke eks es- esa esc ese esk ess ka- kaa kac kae kak kas kca kcc kce kck kcs ke- kea kec kee kek kes kkc kke kkk kks ksa ksc kse ksk kss saa sac sae sak sas sca scc sce sck scs se- sea sec see sek ses sk- ska skc ske skk sks ss- ssa ssc sse ssk sss