a-a a-b a-c a-t aaa aab aac aae aaf aas aat ab- aba abb abc abe abf abs abt ac- aca acb acc ace acf acs act aea aeb aec aee aef aes aet af- afa afb afc afe aff afs aft as- asa asb asc ase asf ass ast at- ata atb atc ate atf ats att baa bab bac bae baf bas bat bba bbb bbc bbe bbf bbs bbt bca bcb bcc bce bcf bcs bct be- bea beb bec bee bef bes bet bfa bfb bfc bfe bff bfs bft bsa bsb bsc bse bsf bss bst bta btb btc bte btf bts btt c-- caa cab cac cae caf cas cat cba cbb cbc cbe cbf cbs cbt cca ccb ccc cce ccf ccs cct ce- cea ceb cec cee cef ces cet cfa cfb cfc cfe cff cfs cft csa csb csc cse csf css cst cta ctb ctc cte ctf cts ctt eaa eab eac eae eaf eas eat eba ebb ebc ebe ebf ebs ebt ec- eca ecb ecc ece ecf ecs ect eea eeb eec eee eef ees eet ef- efa efb efc efe eff efs eft es- esa esb esc ese esf ess est eta etb etc ete etf ets ett faa fab fac fae faf fas fat fba fbb fbc fbe fbf fbs fbt fca fcb fcc fce fcf fcs fct fea feb fec fee fef fes fet ffa ffc ffe fff ffs fft fsa fsb fsc fse fsf fss fst fta ftb ftc fte ftf fts ftt saa sab sac sae saf sas sat sba sbb sbc sbe sbf sbs sbt sca scb scc sce scf scs sct se- sea seb sec see sef ses set sfa sfb sfc sfe sff sfs sft ss- ssa ssb ssc sse ssf sss sst sta stb stc ste stf sts stt taa tab tac tae taf tas tat tba tbb tbc tbe tbf tbs tbt tca tcb tcc tce tcf tcs tct te- tea teb tec tee tef tes tet tfa tfb tfc tfe tff tfs tft tsa tsb tsc tse tsf tss tst tta ttb ttc tte ttf tts ttt