a-a a-b a-c a-t aaa aab aac aaf aak aat ab- aba abb abc abf abk abt ac- aca acb acc acf ack act af- afa afb afc aff afk aft aka akb akc akk at- ata atb atc atf att baa bab bac baf bak bat bba bbb bbc bbf bbk bbt bca bcb bcc bcf bck bct bfa bfb bfc bff bft bka bkb bkc bkf bkk bkt bta btb btc btf btk btt c-- caa cab cac caf cak cat cba cbb cbc cbf cbk cbt cca ccb ccc ccf cck cct cfa cfb cfc cff cfk cft cka ckb ckc ckt cta ctb ctc ctf ctk ctt faa fab fac faf fak fat fba fbb fbc fbf fbk fbt fca fcb fcc fcf fck fct ffa ffc fff ffk fft fka fkb fkc fkf fkk fkt fta ftb ftc ftf ftk ftt k-t ka- kaa kab kac kaf kak kat kba kbb kbc kbf kbk kca kcb kcc kck kct kfa kfc kff kkb kkc kkk kkt kta ktb ktc ktf ktk ktt taa tab tac taf tak tat tba tbb tbc tbf tbk tbt tca tcb tcc tcf tck tct tfa tfb tfc tff tfk tft tka tkb tkc tkk tkt tta ttb ttc ttf ttk ttt