a-a a-c a-t aaa aac aae aan aas aat aax ac- aca acc ace acn acs act acx aea aec aee aen aes aet aex an- ana anc ane ann ans ant anx as- asa asc ase asn ass ast asx at- ata atc ate atn ats att atx ax- axa axe axn axs axt axx c-- caa cac cae can cas cat cax cca ccc cce ccn ccs cct ccx ce- cea cec cee cen ces cet cex cn- cna cnc cne cnn cns cnt cnx csa csc cse csn css cst csx cta ctc cte ctn cts ctt ctx cxc cxs cxt cxx eaa eac eae ean eas eat eax ec- eca ecc ece ecn ecs ect ecx eea eec eee een ees eet eex en- ena enc ene enn ens ent es- esa esc ese esn ess est esx eta etc ete etn ets ett etx ex- exa exc exe exs ext exx naa nac nae nan nas nat nax nca ncc nce ncn ncs nct ncx ne- nea nec nee nen nes net nex nna nnc nne nnn nns nnt nsa nsc nse nsn nss nst nsx nta ntc nte ntn nts ntt ntx nxc nxt saa sac sae san sas sat sax sca scc sce scn scs sct scx se- sea sec see sen ses set sex sna snc sne snn sns snt ss- ssa ssc sse ssn sss sst ssx sta stc ste stn sts stt stx sxc sxn sxs sxt t-x taa tac tae tan tas tat tax tca tcc tce tcn tcs tct tcx te- tea tec tee ten tes tet tex tna tnc tne tnn tns tnt tnx tsa tsc tse tsn tss tst tsx tta ttc tte ttn tts ttt ttx txe txn txs txt xaa xac xan xas xat xcx xee xen xes xet xex xna xnc xns xsa xsc xss xst xtc xts xtx xxx