a-a a-c aaa aac aae aaf aao ac- aca acc ace acf aco aea aec aee aef aeo af- afa afc afe aff afo aoa aoc aoe aof aoo c-- caa cac cae caf cao cca ccc cce ccf cco ce- cea cec cee cef ceo cfa cfc cfe cff cfo co- coa coc coe cof coo eaa eac eae eaf eao ec- eca ecc ece ecf eco eea eec eee eef eeo ef- efa efc efe eff efo eo- eoa eoc eoe eof eoo faa fac fae faf fao fca fcc fce fcf fco fea fec fee fef feo ffa ffc ffe fff ffo foa foc foe fof foo oaa oac oae oaf oao oc- oca occ ocf oco oea oec oee oef oeo of- ofa ofc ofe off ofo oo- ooa ooc oof ooo