a-a a-b a-c a-t aaa aab aac aaf aan aao aat ab- aba abb abc abf abn abo abt ac- aca acb acc acf acn aco act af- afa afb afc aff afn afo aft an- ana anb anc anf ann ano ant aoa aob aoc aof aon aoo aot at- ata atb atc atf atn ato att baa bab bac baf ban bao bat bba bbb bbc bbf bbn bbo bbt bca bcb bcc bcf bcn bco bct bfa bfb bfc bff bfn bfo bft bna bnb bnc bnf bnn bno bnt boa bob boc bof bon boo bot bta btb btc btf btn bto btt c-- caa cab cac caf can cao cat cba cbb cbc cbf cbn cbo cbt cca ccb ccc ccf ccn cco cct cfa cfb cfc cff cfn cfo cft cn- cna cnb cnc cnf cnn cno cnt co- coa cob coc cof con coo cot cta ctb ctc ctf ctn cto ctt faa fab fac faf fan fao fat fba fbb fbc fbf fbn fbo fbt fca fcb fcc fcf fcn fco fct ffa ffc fff ffn ffo fft fna fnb fnc fnf fnn fnt foa fob foc fof fon foo fot fta ftb ftc ftf ftn fto ftt naa nab nac naf nan nao nat nba nbb nbc nbf nbn nbo nbt nca ncb ncc ncf ncn nco nct nfa nfb nfc nff nfn nfo nft nna nnb nnc nnf nnn nno nnt no- noa nob noc nof non noo not nta ntb ntc ntf ntn nto ntt oaa oab oac oaf oan oao oat ob- oba obb obc obf obn obo obt oc- oca ocb occ ocf ocn oco oct of- ofa ofb ofc off ofn ofo oft on- ona onb onc onf onn ono ont oo- ooa oob ooc oof oon ooo oot ot- ota otb otc otf otn oto ott taa tab tac taf tan tao tat tba tbb tbc tbf tbn tbo tbt tca tcb tcc tcf tcn tco tct tfa tfb tfc tff tfn tfo tft tna tnb tnc tnf tnn tno tnt to- toa tob toc tof ton too tot tta ttb ttc ttf ttn tto ttt