a-a a-c aaa aac aae aaf aak aao ac- aca acc ace acf ack aco aea aec aee aef aek aeo af- afa afc afe aff afk afo aka akc ake akk ako aoa aoc aoe aof aok aoo c-- caa cac cae caf cak cao cca ccc cce ccf cck cco ce- cea cec cee cef cek ceo cfa cfc cfe cff cfk cfo cka ckc cko co- coa coc coe cof cok coo eaa eac eae eaf eak eao ec- eca ecc ece ecf eck eco eea eec eee eef eek eeo ef- efa efc efe eff efo eka ekc eke ekf eko eo- eoa eoc eoe eof eok eoo faa fac fae faf fak fao fca fcc fce fcf fck fco fea fec fee fef fek feo ffa ffc ffe fff ffk ffo fka fkc fkf fkk foa foc foe fof fok foo ka- kaa kac kae kaf kak kao kca kcc kce kck ke- kea kec kee kef kek keo kfa kfc kff kfo kkc kke kkk koa koc koe kof kok koo oaa oac oae oaf oak oao oc- oca occ ocf ock oco oea oec oee oef oeo of- ofa ofc ofe off ofo oka okc oke okk oko oo- ooa ooc oof ook ooo