-er a-a a-b a-t aaa aab aae aar aas aat aau aax ab- aba abb abe abr abs abt abu abx aea aeb aee aer aes aet aeu aex ar- ara arb are arr ars art aru arx as- asa asb ase asr ass ast asu asx at- ata atb ate atr ats att atu atx au- aua aub aue aur aus aut aux ax- axa axe axr axs axt axx b-u baa bab bae bar bas bat bau bax bba bbb bbe bbr bbs bbt bbu bbx be- bea beb bee ber bes bet beu bex bra brb bre brr brs brt bru brx bsa bsb bse bsr bss bst bsu bsx bta btb bte btr bts btt btu btx bua bub bue bur bus but buu bux bxb bxx eaa eab eae ear eas eat eau eax eba ebb ebe ebr ebs ebt ebu ebx eea eeb eee eer ees eet eex era erb ere err ers ert eru es- esa esb ese esr ess est esu esx eta etb ete etr ets ett etu etx eu- eua eub eue eur eus eut eux ex- exa exe exr exs ext exu exx ra- raa rab rae rar ras rat rau rax rba rbb rbe rbr rbs rbt rbu rbx re- rea reb ree rer res ret reu rex rra rrb rrr rrs rrt rru rsa rsb rse rsr rss rst rsu rsx rta rtb rte rtr rts rtt rtu rtx rua rub rue rur rus rut ruu rux rxr rxs saa sab sae sar sas sat sau sax sba sbb sbe sbr sbs sbt sbu sbx se- sea seb see ser ses set seu sex sr- sra srb sre srr srs srt srx ss- ssa ssb sse ssr sss sst ssu ssx sta stb ste str sts stt stu stx sua sub sue sur sus sut suu sux sxs sxt sxu t-x taa tab tae tar tas tat tau tax tba tbb tbe tbr tbs tbt tbu te- tea teb tee ter tes tet teu tex tra trb tre trr trs trt tru trx tsa tsb tse tsr tss tst tsu tsx tta ttb tte ttr tts ttt ttu ttx tua tub tue tur tus tut tuu tux txe txs txt txu ua- uaa uab uae uar uas uat uau uba ubb ube ubr ubs ubt ubu ubx uea ueb uee uer ues uet ur- ura urb ure urr urs urt uru urx usa usb use usr uss ust usu usx uta utb ute utr uts utt utu utx uua uue uur uus uut uuu uxb uxr uxt uxu xaa xar xas xat xau xbe xbr xbx xee xer xes xet xeu xex xrt xrx xsa xsb xss xst xtr xts xtx xue xus xxx