a-a a-b a-c a-t aaa aab aac aae aak aan aat ab- aba abb abc abe abk abn abt ac- aca acb acc ace ack acn act aea aeb aec aee aek aen aet aka akb akc ake akk akn an- ana anb anc ane ank ann ant at- ata atb atc ate atn att baa bab bac bae bak ban bat bba bbb bbc bbe bbk bbn bbt bca bcb bcc bce bck bcn bct be- bea beb bec bee bek ben bet bka bkb bkc bke bkk bkn bkt bna bnb bnc bne bnk bnn bnt bta btb btc bte btk btn btt c-- caa cab cac cae cak can cat cba cbb cbc cbe cbk cbn cbt cca ccb ccc cce cck ccn cct ce- cea ceb cec cee cek cen cet cka ckb ckc ckt cn- cna cnb cnc cne cnn cnt cta ctb ctc cte ctk ctn ctt eaa eab eac eae eak ean eat eba ebb ebc ebe ebk ebn ebt ec- eca ecb ecc ece eck ecn ect eea eeb eec eee eek een eet eka ekb ekc eke ekt en- ena enb enc ene enk enn ent eta etb etc ete etk etn ett k-t ka- kaa kab kac kae kak kan kat kba kbb kbc kbe kbk kbn kca kcb kcc kce kck kcn kct ke- kea keb kec kee kek ken ket kkb kkc kke kkk kkn kkt kn- kna knc kne knk knn knt kta ktb ktc kte ktk ktn ktt naa nab nac nae nak nan nat nba nbb nbc nbe nbk nbn nbt nca ncb ncc nce nck ncn nct ne- nea neb nec nee nek nen net nka nkc nke nkk nkn nkt nna nnb nnc nne nnk nnn nnt nta ntb ntc nte ntk ntn ntt taa tab tac tae tak tan tat tba tbb tbc tbe tbk tbn tbt tca tcb tcc tce tck tcn tct te- tea teb tec tee tek ten tet tka tkb tkc tke tkk tkt tna tnb tnc tne tnk tnn tnt tta ttb ttc tte ttk ttn ttt