a-a a-b a-i a-t aaa aab aai aao aar aas aat aax ab- aba abb abi abo abr abs abt abx ai- aia aib aii aio air ais ait aix aoa aob aoi aoo aor aos aot aox ar- ara arb ari aro arr ars art arx as- asa asb asi aso asr ass ast asx at- ata atb ati ato atr ats att atx ax- axa axi axo axr axs axt axx baa bab bai bao bar bas bat bax bba bbb bbi bbo bbr bbs bbt bbx bi- bia bib bii bio bir bis bit bix boa bob boi boo bor bos bot box bra brb bri bro brr brs brt brx bsa bsb bsi bso bsr bss bst bsx bta btb bti bto btr bts btt btx bxb bxi bxo bxx ia- iaa iab iai iao iar ias iat iba ibb ibi ibo ibr ibs ibt ibx iia iib iii iio iir iis iit iix io- ioa iob ioi ioo ior ios iot ir- ira irb iri iro irr irs irt irx is- isa isb isi iso isr iss ist ita itb iti ito its itt itx ixi o-i oaa oab oai oao oar oas oat oax ob- oba obb obi obo obr obs obt obx oia oib oii oio oir ois oit oo- ooa oob ooi ooo oor oos oot oox or- ora orb ori oro orr ors ort orx os- osa osb osi oso osr oss ost osx ot- ota otb oti oto otr ots ott ox- oxa oxb oxi oxo oxt oxx ra- raa rab rai rao rar ras rat rax rba rbb rbi rbo rbr rbs rbt rbx ria rib rii rio rir ris rit rix roa rob roi roo ror ros rot rox rra rrb rri rrr rrs rrt rsa rsb rsi rso rsr rss rst rsx rta rtb rti rto rtr rts rtt rtx rxr rxs saa sab sai sao sar sas sat sax sba sbb sbi sbo sbr sbs sbt sbx sia sib sii sio sir sis sit six soa sob soi soo sor sos sot sox sr- sra srb sri sro srr srs srt srx ss- ssa ssb ssi sso ssr sss sst ssx sta stb sti sto str sts stt stx sxi sxs sxt t-x taa tab tai tao tar tas tat tax tba tbb tbi tbo tbr tbs tbt tia tib tii tio tir tis tit tix to- toa tob toi too tor tos tot tox tra trb tri tro trr trs trt trx tsa tsb tsi tso tsr tss tst tsx tta ttb tti tto ttr tts ttt ttx txi txs txt xaa xar xas xat xbr xbx xia xii xio xis xit xix xoa xoi xoo xor xos xot xox xrt xrx xsa xsb xsi xss xst xti xtr xts xtx xxi xxo xxx