c-- ccc ccf cco ccp ccs cct cfc cff cfo cfp cfs cft co- coc cof coo cop cos cot cpc cpf cpo cpp cps cpt csc csf cso csp css cst ctc ctf cto ctp cts ctt fcc fcf fco fcp fcs fct ffc fff ffo ffp ffs fft foc fof foo fop fos fot fpc fpo fpp fps fpt fsc fsf fso fsp fss fst ftc ftf fto ftp fts ftt oc- occ ocf oco ocp ocs oct of- ofc off ofo ofp ofs oft oo- ooc oof ooo oop oos oot op- opc opf opo opp ops opt os- osc osf oso osp oss ost ot- otc otf oto otp ots ott p-p pcc pcf pco pcp pcs pct pfc pff pfo pfp pfs pft poc pof poo pop pos pot ppc ppf ppo ppp pps ppt ps- psc psf pso psp pss pst pt- ptc ptf pto ptp pts ptt scc scf sco scp scs sct sfc sff sfo sfp sfs sft soc sof soo sop sos sot spc spf spo spp sps spt ss- ssc ssf sso ssp sss sst stc stf sto stp sts stt tcc tcf tco tcp tcs tct tfc tff tfo tfp tfs tft to- toc tof too top tos tot tpc tpf tpo tpp tps tpt tsc tsf tso tsp tss tst ttc ttf tto ttp tts ttt