c-- ccc cce cck cco ccs cct ce- cec cee cek ceo ces cet ckc cko cks ckt co- coc coe cok coo cos cot csc cse csk cso css cst ctc cte ctk cto cts ctt ec- ecc ece eck eco ecs ect eec eee eek eeo ees eet ekc eke eko eks ekt eo- eoc eoe eok eoo eos eot es- esc ese esk eso ess est etc ete etk eto ets ett k-t kcc kce kck kcs kct ke- kec kee kek keo kes ket kkc kke kkk kks kkt koc koe kok koo kos kot ksc kse ksk kso kss kst ktc kte ktk kto kts ktt oc- occ ock oco ocs oct oec oee oeo oes oet okc oke okk oko oks oo- ooc ook ooo oos oot os- osc ose osk oso oss ost ot- otc ote otk oto ots ott scc sce sck sco scs sct se- sec see sek seo ses set sk- skc ske skk sko sks skt soc soe sok soo sos sot ss- ssc sse ssk sso sss sst stc ste stk sto sts stt tcc tce tck tco tcs tct te- tec tee tek teo tes tet tkc tke tkk tko tks tkt to- toc toe tok too tos tot tsc tse tsk tso tss tst ttc tte ttk tto tts ttt