a-a a-c a-t aaa aac aaf aao aat ac- aca acc acf aco act af- afa afc aff afo aft aoa aoc aof aoo aot at- ata atc atf ato att c-- caa cac caf cao cat cca ccc ccf cco cct cfa cfc cff cfo cft co- coa coc cof coo cot cta ctc ctf cto ctt faa fac faf fao fat fca fcc fcf fco fct ffa ffc fff ffo fft foa foc fof foo fot fta ftc ftf fto ftt oaa oac oaf oao oat oc- oca occ ocf oco oct of- ofa ofc off ofo oft oo- ooa ooc oof ooo oot ot- ota otc otf oto ott taa tac taf tao tat tca tcc tcf tco tct tfa tfc tff tfo tft to- toa toc tof too tot tta ttc ttf tto ttt