a-a a-c a-t aaa aac aan aar aas aat aax ac- aca acc acn acr acs act acx an- ana anc ann anr ans ant anx ar- ara arc arn arr ars art arx as- asa asc asn asr ass ast asx at- ata atc atn atr ats att atx ax- axa axn axr axs axt axx c-- caa cac can car cas cat cax cca ccc ccn ccr ccs cct ccx cn- cna cnc cnn cnr cns cnt cnx cra crc crn crr crs crt crx csa csc csn csr css cst csx cta ctc ctn ctr cts ctt ctx cxc cxr cxs cxt cxx naa nac nan nar nas nat nax nca ncc ncn ncr ncs nct ncx nna nnc nnn nns nnt nra nrc nrn nrr nrs nrt nrx nsa nsc nsn nsr nss nst nsx nta ntc ntn ntr nts ntt ntx nxc nxt ra- raa rac ran rar ras rat rax rca rcc rcn rcr rcs rct rcx rna rnc rnn rnr rns rnt rra rrc rrn rrr rrs rrt rsa rsc rsn rsr rss rst rsx rta rtc rtn rtr rts rtt rtx rxr rxs saa sac san sar sas sat sax sca scc scn scr scs sct scx sna snc snn snr sns snt sr- sra src srn srr srs srt srx ss- ssa ssc ssn ssr sss sst ssx sta stc stn str sts stt stx sxc sxn sxs sxt t-x taa tac tan tar tas tat tax tca tcc tcn tcr tcs tct tcx tna tnc tnn tnr tns tnt tnx tra trc trn trr trs trt trx tsa tsc tsn tsr tss tst tsx tta ttc ttn ttr tts ttt ttx txn txs txt xaa xac xan xar xas xat xcr xcx xna xnc xns xrc xrt xrx xsa xsc xss xst xtc xtr xts xtx xxx