-er bbb bbe bbm bbo bbr bbs bbx be- beb bee bem beo ber bes bex bmb bme bmm bmo bmr bms bmx bob boe bom boo bor bos box brb bre brm bro brr brs brx bsb bse bsm bso bsr bss bsx bxb bxm bxo bxx ebb ebe ebm ebo ebr ebs ebx eeb eee eem eeo eer ees eex em- emb eme emm emo emr ems emx eo- eob eoe eom eoo eor eos erb ere erm ero err ers es- esb ese esm eso esr ess esx ex- exe exo exr exs exx m-o m-r mbb mbe mbm mbo mbr mbs mbx meb mee mem meo mer mes mex mmb mme mmm mmo mmr mms mmx mob moe mom moo mor mos mox mrb mre mrm mro mrr mrs mrx msb mse msm mso msr mss msx mxr mxs ob- obb obe obm obo obr obs obx oeb oee oem oeo oer oes oex om- omb ome omm omo omr oms omx oo- oob oom ooo oor oos oox or- orb ore orm oro orr ors orx os- osb ose osm oso osr oss osx ox- oxb oxo oxx rbb rbe rbm rbo rbr rbs rbx re- reb ree rem reo rer res rex rmb rme rmm rmo rmr rms rmx rob roe rom roo ror ros rox rrb rrm rrr rrs rsb rse rsm rso rsr rss rsx rxr rxs sbb sbe sbm sbo sbr sbs sbx se- seb see sem seo ser ses sex smb sme smm smo smr sms smx sob soe som soo sor sos sox sr- srb sre srm sro srr srs srx ss- ssb sse ssm sso ssr sss ssx sxm sxs xbe xbr xbx xee xem xer xes xex xmm xmo xmr xms xmx xom xoo xor xos xox xrx xsb xsm xss xxo xxx