a-a a-b a-c a-t aaa aab aac aae aak aat ab- aba abb abc abe abk abt ac- aca acb acc ace ack act aea aeb aec aee aek aet aka akb akc ake akk at- ata atb atc ate att baa bab bac bae bak bat bba bbb bbc bbe bbk bbt bca bcb bcc bce bck bct be- bea beb bec bee bek bet bka bkb bkc bke bkk bkt bta btb btc bte btk btt c-- caa cab cac cae cak cat cba cbb cbc cbe cbk cbt cca ccb ccc cce cck cct ce- cea ceb cec cee cek cet cka ckb ckc ckt cta ctb ctc cte ctk ctt eaa eab eac eae eak eat eba ebb ebc ebe ebk ebt ec- eca ecb ecc ece eck ect eea eeb eec eee eek eet eka ekb ekc eke ekt eta etb etc ete etk ett k-t ka- kaa kab kac kae kak kat kba kbb kbc kbe kbk kca kcb kcc kce kck kct ke- kea keb kec kee kek ket kkb kkc kke kkk kkt kta ktb ktc kte ktk ktt taa tab tac tae tak tat tba tbb tbc tbe tbk tbt tca tcb tcc tce tck tct te- tea teb tec tee tek tet tka tkb tkc tke tkk tkt tta ttb ttc tte ttk ttt