a-a a-b a-c a-t aaa aab aac aae aan aas aat ab- aba abb abc abe abn abs abt ac- aca acb acc ace acn acs act aea aeb aec aee aen aes aet an- ana anb anc ane ann ans ant as- asa asb asc ase asn ass ast at- ata atb atc ate atn ats att baa bab bac bae ban bas bat bba bbb bbc bbe bbn bbs bbt bca bcb bcc bce bcn bcs bct be- bea beb bec bee ben bes bet bna bnb bnc bne bnn bns bnt bsa bsb bsc bse bsn bss bst bta btb btc bte btn bts btt c-- caa cab cac cae can cas cat cba cbb cbc cbe cbn cbs cbt cca ccb ccc cce ccn ccs cct ce- cea ceb cec cee cen ces cet cn- cna cnb cnc cne cnn cns cnt csa csb csc cse csn css cst cta ctb ctc cte ctn cts ctt eaa eab eac eae ean eas eat eba ebb ebc ebe ebn ebs ebt ec- eca ecb ecc ece ecn ecs ect eea eeb eec eee een ees eet en- ena enb enc ene enn ens ent es- esa esb esc ese esn ess est eta etb etc ete etn ets ett naa nab nac nae nan nas nat nba nbb nbc nbe nbn nbs nbt nca ncb ncc nce ncn ncs nct ne- nea neb nec nee nen nes net nna nnb nnc nne nnn nns nnt nsa nsb nsc nse nsn nss nst nta ntb ntc nte ntn nts ntt saa sab sac sae san sas sat sba sbb sbc sbe sbn sbs sbt sca scb scc sce scn scs sct se- sea seb sec see sen ses set sna snb snc sne snn sns snt ss- ssa ssb ssc sse ssn sss sst sta stb stc ste stn sts stt taa tab tac tae tan tas tat tba tbb tbc tbe tbn tbs tbt tca tcb tcc tce tcn tcs tct te- tea teb tec tee ten tes tet tna tnb tnc tne tnn tns tnt tsa tsb tsc tse tsn tss tst tta ttb ttc tte ttn tts ttt