a-a a-b a-c a-t aaa aab aac aak aat ab- aba abb abc abk abt ac- aca acb acc ack act aka akb akc akk at- ata atb atc att baa bab bac bak bat bba bbb bbc bbk bbt bca bcb bcc bck bct bka bkb bkc bkk bkt bta btb btc btk btt c-- caa cab cac cak cat cba cbb cbc cbk cbt cca ccb ccc cck cct cka ckb ckc ckt cta ctb ctc ctk ctt k-t ka- kaa kab kac kak kat kba kbb kbc kbk kca kcb kcc kck kct kkb kkc kkk kkt kta ktb ktc ktk ktt taa tab tac tak tat tba tbb tbc tbk tbt tca tcb tcc tck tct tka tkb tkc tkk tkt tta ttb ttc ttk ttt