c-- ccc ccf cck cco ccr ccs cct cfc cff cfk cfo cfr cfs cft ckc cko cks ckt co- coc cof cok coo cor cos cot crc crf crk cro crr crs crt csc csf csk cso csr css cst ctc ctf ctk cto ctr cts ctt fcc fcf fck fco fcr fcs fct ffc fff ffk ffo ffr ffs fft fkc fkf fkk fkt foc fof fok foo for fos fot frc frf frk fro frr frs frt fsc fsf fsk fso fsr fss fst ftc ftf ftk fto ftr fts ftt k-t kcc kck kcr kcs kct kfc kff kfo kfs kkc kkk kkr kks kkt koc kof kok koo kor kos kot krc krf krk kro krr krs krt ksc ksf ksk kso ksr kss kst ktc ktf ktk kto ktr kts ktt oc- occ ocf ock oco ocr ocs oct of- ofc off ofo ofr ofs oft okc okk oko okr oks oo- ooc oof ook ooo oor oos oot or- orc orf ork oro orr ors ort os- osc osf osk oso osr oss ost ot- otc otf otk oto otr ots ott rcc rcf rco rcr rcs rct rfc rff rfk rfo rfr rfs rft rkc rkf rkk rko rks rkt roc rof rok roo ror ros rot rrc rrf rrk rrr rrs rrt rsc rsf rsk rso rsr rss rst rtc rtf rtk rto rtr rts rtt scc scf sck sco scr scs sct sfc sff sfk sfo sfr sfs sft sk- skc skf skk sko skr sks skt soc sof sok soo sor sos sot sr- src srf srk sro srr srs srt ss- ssc ssf ssk sso ssr sss sst stc stf stk sto str sts stt tcc tcf tck tco tcr tcs tct tfc tff tfk tfo tfr tfs tft tkc tkk tko tkr tks tkt to- toc tof tok too tor tos tot trc trf trk tro trr trs trt tsc tsf tsk tso tsr tss tst ttc ttf ttk tto ttr tts ttt