a-a a-b a-c a-t aaa aab aac aae aaf aan aat ab- aba abb abc abe abf abn abt ac- aca acb acc ace acf acn act aea aeb aec aee aef aen aet af- afa afb afc afe aff afn aft an- ana anb anc ane anf ann ant at- ata atb atc ate atf atn att baa bab bac bae baf ban bat bba bbb bbc bbe bbf bbn bbt bca bcb bcc bce bcf bcn bct be- bea beb bec bee bef ben bet bfa bfb bfc bfe bff bfn bft bna bnb bnc bne bnf bnn bnt bta btb btc bte btf btn btt c-- caa cab cac cae caf can cat cba cbb cbc cbe cbf cbn cbt cca ccb ccc cce ccf ccn cct ce- cea ceb cec cee cef cen cet cfa cfb cfc cfe cff cfn cft cn- cna cnb cnc cne cnf cnn cnt cta ctb ctc cte ctf ctn ctt eaa eab eac eae eaf ean eat eba ebb ebc ebe ebf ebn ebt ec- eca ecb ecc ece ecf ecn ect eea eeb eec eee eef een eet ef- efa efb efc efe eff eft en- ena enb enc ene enf enn ent eta etb etc ete etf etn ett faa fab fac fae faf fan fat fba fbb fbc fbe fbf fbn fbt fca fcb fcc fce fcf fcn fct fea feb fec fee fef fen fet ffa ffc ffe fff ffn fft fna fnb fnc fne fnf fnn fnt fta ftb ftc fte ftf ftn ftt naa nab nac nae naf nan nat nba nbb nbc nbe nbf nbn nbt nca ncb ncc nce ncf ncn nct ne- nea neb nec nee nef nen net nfa nfb nfc nfe nff nfn nft nna nnb nnc nne nnf nnn nnt nta ntb ntc nte ntf ntn ntt taa tab tac tae taf tan tat tba tbb tbc tbe tbf tbn tbt tca tcb tcc tce tcf tcn tct te- tea teb tec tee tef ten tet tfa tfb tfc tfe tff tfn tft tna tnb tnc tne tnf tnn tnt tta ttb ttc tte ttf ttn ttt