a-a a-c a-t aaa aac aaf aao aat aax ac- aca acc acf aco act acx af- afa afc aff afo aft afx aoa aoc aof aoo aot aox at- ata atc atf ato att atx ax- axa axo axt axx c-- caa cac caf cao cat cax cca ccc ccf cco cct ccx cfa cfc cff cfo cft cfx co- coa coc cof coo cot cox cta ctc ctf cto ctt ctx cxc cxf cxo cxt cxx faa fac faf fao fat fax fca fcc fcf fco fct fcx ffa ffc fff ffo fft ffx foa foc fof foo fot fox fta ftc ftf fto ftt ftx fxt fxx oaa oac oaf oao oat oax oc- oca occ ocf oco oct ocx of- ofa ofc off ofo oft ofx oo- ooa ooc oof ooo oot oox ot- ota otc otf oto ott ox- oxa oxc oxf oxo oxt oxx t-x taa tac taf tao tat tax tca tcc tcf tco tct tcx tfa tfc tff tfo tft tfx to- toa toc tof too tot tox tta ttc ttf tto ttt ttx txf txt xaa xac xaf xat xcf xcx xfa xft xfx xoa xoc xof xoo xot xox xtc xtf xtx xxo xxx