a-a a-c a-t aaa aac aaf aao aar aas aat aax ac- aca acc acf aco acr acs act acx af- afa afc aff afo afr afs aft afx aoa aoc aof aoo aor aos aot aox ar- ara arc arf aro arr ars art arx as- asa asc asf aso asr ass ast asx at- ata atc atf ato atr ats att atx ax- axa axo axr axs axt axx c-- caa cac caf cao car cas cat cax cca ccc ccf cco ccr ccs cct ccx cfa cfc cff cfo cfr cfs cft cfx co- coa coc cof coo cor cos cot cox cra crc crf cro crr crs crt crx csa csc csf cso csr css cst csx cta ctc ctf cto ctr cts ctt ctx cxc cxf cxo cxr cxs cxt cxx faa fac faf fao far fas fat fax fca fcc fcf fco fcr fcs fct fcx ffa ffc fff ffo ffr ffs fft ffx foa foc fof foo for fos fot fox fra frc frf fro frr frs frt fsa fsc fsf fso fsr fss fst fsx fta ftc ftf fto ftr fts ftt ftx fxr fxs fxt fxx oaa oac oaf oao oar oas oat oax oc- oca occ ocf oco ocr ocs oct ocx of- ofa ofc off ofo ofr ofs oft ofx oo- ooa ooc oof ooo oor oos oot oox or- ora orc orf oro orr ors ort orx os- osa osc osf oso osr oss ost osx ot- ota otc otf oto otr ots ott ox- oxa oxc oxf oxo oxt oxx ra- raa rac raf rao rar ras rat rax rca rcc rcf rco rcr rcs rct rcx rfa rfc rff rfo rfr rfs rft roa roc rof roo ror ros rot rox rra rrc rrf rrr rrs rrt rsa rsc rsf rso rsr rss rst rsx rta rtc rtf rto rtr rts rtt rtx rxr rxs saa sac saf sao sar sas sat sax sca scc scf sco scr scs sct scx sfa sfc sff sfo sfr sfs sft sfx soa soc sof soo sor sos sot sox sr- sra src srf sro srr srs srt srx ss- ssa ssc ssf sso ssr sss sst ssx sta stc stf sto str sts stt stx sxc sxs sxt t-x taa tac taf tao tar tas tat tax tca tcc tcf tco tcr tcs tct tcx tfa tfc tff tfo tfr tfs tft tfx to- toa toc tof too tor tos tot tox tra trc trf tro trr trs trt trx tsa tsc tsf tso tsr tss tst tsx tta ttc ttf tto ttr tts ttt ttx txf txs txt xaa xac xaf xar xas xat xcf xcr xcx xfa xfs xft xfx xoa xoc xof xoo xor xos xot xox xrc xrf xrt xrx xsa xsc xss xst xtc xtf xtr xts xtx xxo xxx