c-- ccc cce cck cco ccs ce- cec cee cek ceo ces ckc cko cks co- coc coe cok coo cos csc cse csk cso css ec- ecc ece eck eco ecs eec eee eek eeo ees ekc eke eko eks eo- eoc eoe eok eoo eos es- esc ese esk eso ess kcc kce kck kcs ke- kec kee kek keo kes kkc kke kkk kks koc koe kok koo kos ksc kse ksk kso kss oc- occ ock oco ocs oec oee oeo oes okc oke okk oko oks oo- ooc ook ooo oos os- osc ose osk oso oss scc sce sck sco scs se- sec see sek seo ses sk- skc ske skk sko sks soc soe sok soo sos ss- ssc sse ssk sso sss