-er b-u bbb bbe bbf bbo bbr bbs bbt bbu bbx be- beb bee bef beo ber bes bet beu bex bfb bfe bff bfo bfr bfs bft bfu bfx bob boe bof boo bor bos bot bou box brb bre brf bro brr brs brt bru brx bsb bse bsf bso bsr bss bst bsu bsx btb bte btf bto btr bts btt btu btx bub bue buf buo bur bus but buu bux bxb bxo bxx ebb ebe ebf ebo ebr ebs ebt ebu ebx eeb eee eef eeo eer ees eet eex ef- efb efe eff efo efr efs eft efx eo- eob eoe eof eoo eor eos eot eou erb ere erf ero err ers ert eru es- esb ese esf eso esr ess est esu esx etb ete etf eto etr ets ett etu etx eu- eub eue euf eur eus eut eux ex- exe exo exr exs ext exu exx fbb fbe fbf fbo fbr fbs fbt fbu fbx feb fee fef feo fer fes fet feu fex ffe fff ffo ffr ffs fft ffu ffx fob foe fof foo for fos fot fou fox frb fre frf fro frr frs frt fru fsb fse fsf fso fsr fss fst fsu fsx ftb fte ftf fto ftr fts ftt ftu ftx fub fue fuf fuo fur fus fut fuu fux fxe fxr fxs fxt fxu fxx ob- obb obe obf obo obr obs obt obu obx oeb oee oef oeo oer oes oet oex of- ofb ofe off ofo ofr ofs oft ofu ofx oo- oob oof ooo oor oos oot oox or- orb ore orf oro orr ors ort oru orx os- osb ose osf oso osr oss ost osu osx ot- otb ote otf oto otr ots ott otu ou- oue ouf ouo our ous out ox- oxb oxf oxo oxt oxx rbb rbe rbf rbo rbr rbs rbt rbu rbx re- reb ree ref reo rer res ret reu rex rfb rfe rff rfo rfr rfs rft rfu rob roe rof roo ror ros rot rou rox rrb rrf rrr rrs rrt rru rsb rse rsf rso rsr rss rst rsu rsx rtb rte rtf rto rtr rts rtt rtu rtx rub rue ruf ruo rur rus rut ruu rux rxr rxs sbb sbe sbf sbo sbr sbs sbt sbu sbx se- seb see sef seo ser ses set seu sex sfb sfe sff sfo sfr sfs sft sfu sfx sob soe sof soo sor sos sot sou sox sr- srb sre srf sro srr srs srt srx ss- ssb sse ssf sso ssr sss sst ssu ssx stb ste stf sto str sts stt stu stx sub sue suf suo sur sus sut suu sux sxs sxt sxu t-x tbb tbe tbf tbo tbr tbs tbt tbu te- teb tee tef teo ter tes tet teu tex tfb tfe tff tfo tfr tfs tft tfu tfx to- tob toe tof too tor tos tot tou tox trb tre trf tro trr trs trt tru trx tsb tse tsf tso tsr tss tst tsu tsx ttb tte ttf tto ttr tts ttt ttu ttx tub tue tuf tuo tur tus tut tuu tux txe txf txs txt txu ubb ube ubf ubo ubr ubs ubt ubu ubx ueb uee uef uer ues uet ufe uff ufo ufr ufs uft ufu ufx uob uoe uoo uor uos uot uox ur- urb ure urf uro urr urs urt uru urx usb use usf uso usr uss ust usu usx utb ute utf uto utr uts utt utu utx uue uur uus uut uuu uxb uxf uxo uxr uxt uxu xbe xbr xbx xee xer xes xet xeu xex xfe xfs xft xfx xof xoo xor xos xot xox xrf xrt xrx xsb xss xst xtf xtr xts xtx xue xus xxo xxx