c-- ccc cce ccf cco ccs cct ce- cec cee cef ceo ces cet cfc cfe cff cfo cfs cft co- coc coe cof coo cos cot csc cse csf cso css cst ctc cte ctf cto cts ctt ec- ecc ece ecf eco ecs ect eec eee eef eeo ees eet ef- efc efe eff efo efs eft eo- eoc eoe eof eoo eos eot es- esc ese esf eso ess est etc ete etf eto ets ett fcc fce fcf fco fcs fct fec fee fef feo fes fet ffc ffe fff ffo ffs fft foc foe fof foo fos fot fsc fse fsf fso fss fst ftc fte ftf fto fts ftt oc- occ ocf oco ocs oct oec oee oef oeo oes oet of- ofc ofe off ofo ofs oft oo- ooc oof ooo oos oot os- osc ose osf oso oss ost ot- otc ote otf oto ots ott scc sce scf sco scs sct se- sec see sef seo ses set sfc sfe sff sfo sfs sft soc soe sof soo sos sot ss- ssc sse ssf sso sss sst stc ste stf sto sts stt tcc tce tcf tco tcs tct te- tec tee tef teo tes tet tfc tfe tff tfo tfs tft to- toc toe tof too tos tot tsc tse tsf tso tss tst ttc tte ttf tto tts ttt