c-- ccc ccf cco ccr cct ccx cfc cff cfo cfr cft cfx co- coc cof coo cor cot cox crc crf cro crr crt crx ctc ctf cto ctr ctt ctx cxc cxf cxo cxr cxt cxx fcc fcf fco fcr fct fcx ffc fff ffo ffr fft ffx foc fof foo for fot fox frc frf fro frr frt ftc ftf fto ftr ftt ftx fxr fxt fxx oc- occ ocf oco ocr oct ocx of- ofc off ofo ofr oft ofx oo- ooc oof ooo oor oot oox or- orc orf oro orr ort orx ot- otc otf oto otr ott ox- oxc oxf oxo oxt oxx rcc rcf rco rcr rct rcx rfc rff rfo rfr rft roc rof roo ror rot rox rrc rrf rrr rrt rtc rtf rto rtr rtt rtx rxr t-x tcc tcf tco tcr tct tcx tfc tff tfo tfr tft tfx to- toc tof too tor tot tox trc trf tro trr trt trx ttc ttf tto ttr ttt ttx txf txt xcf xcr xcx xft xfx xoc xof xoo xor xot xox xrc xrf xrt xrx xtc xtf xtr xtx xxo xxx