-er bbb bbe bbm bbo bbr bbs bbt be- beb bee bem beo ber bes bet bmb bme bmm bmo bmr bms bmt bob boe bom boo bor bos bot brb bre brm bro brr brs brt bsb bse bsm bso bsr bss bst btb bte btm bto btr bts btt ebb ebe ebm ebo ebr ebs ebt eeb eee eem eeo eer ees eet em- emb eme emm emo emr ems emt eo- eob eoe eom eoo eor eos eot erb ere erm ero err ers ert es- esb ese esm eso esr ess est etb ete etm eto etr ets ett m-o m-r mbb mbe mbm mbo mbr mbs mbt meb mee mem meo mer mes met mmb mme mmm mmo mmr mms mmt mob moe mom moo mor mos mot mrb mre mrm mro mrr mrs mrt msb mse msm mso msr mss mst mtb mte mtm mto mtr mts mtt ob- obb obe obm obo obr obs obt oeb oee oem oeo oer oes oet om- omb ome omm omo omr oms omt oo- oob oom ooo oor oos oot or- orb ore orm oro orr ors ort os- osb ose osm oso osr oss ost ot- otb ote otm oto otr ots ott rbb rbe rbm rbo rbr rbs rbt re- reb ree rem reo rer res ret rmb rme rmm rmo rmr rms rmt rob roe rom roo ror ros rot rrb rrm rrr rrs rrt rsb rse rsm rso rsr rss rst rtb rte rtm rto rtr rts rtt sbb sbe sbm sbo sbr sbs sbt se- seb see sem seo ser ses set smb sme smm smo smr sms smt sob soe som soo sor sos sot sr- srb sre srm sro srr srs srt ss- ssb sse ssm sso ssr sss sst stb ste stm sto str sts stt tbb tbe tbm tbo tbr tbs tbt te- teb tee tem teo ter tes tet tmb tme tmm tmo tmr tms tmt to- tob toe tom too tor tos tot trb tre trm tro trr trs trt tsb tse tsm tso tsr tss tst ttb tte ttm tto ttr tts ttt