-er bbb bbe bbk bbm bbo bbr bbs bbx be- beb bee bek bem beo ber bes bex bkb bke bkk bkm bko bkr bks bkx bmb bme bmk bmm bmo bmr bms bmx bob boe bok bom boo bor bos box brb bre brk brm bro brr brs brx bsb bse bsk bsm bso bsr bss bsx bxb bxm bxo bxx ebb ebe ebk ebm ebo ebr ebs ebx eeb eee eek eem eeo eer ees eex ekb eke eko ekr eks em- emb eme emk emm emo emr ems emx eo- eob eoe eok eom eoo eor eos erb ere erk erm ero err ers es- esb ese esk esm eso esr ess esx ex- exe exo exr exs exx kbb kbe kbk kbm kbo kbr kbs kbx ke- keb kee kek kem keo ker kes kex kkb kke kkk kkm kkr kks kmb kme kmk kmm kmo kms kob koe kok kom koo kor kos krk kro krr krs ksb kse ksk ksm kso ksr kss kxm kxo m-o m-r mbb mbe mbk mbm mbo mbr mbs mbx meb mee mek mem meo mer mes mex mkb mke mkk mkm mko mkr mks mkx mmb mme mmk mmm mmo mmr mms mmx mob moe mok mom moo mor mos mox mrb mre mrk mrm mro mrr mrs mrx msb mse msk msm mso msr mss msx mxr mxs ob- obb obe obk obm obo obr obs obx oeb oee oem oeo oer oes oex okb oke okk oko okr oks om- omb ome omm omo omr oms omx oo- oob ook oom ooo oor oos oox or- orb ore ork orm oro orr ors orx os- osb ose osk osm oso osr oss osx ox- oxb oxo oxx rbb rbe rbk rbm rbo rbr rbs rbx re- reb ree rek rem reo rer res rex rkb rke rkk rkm rko rks rmb rme rmm rmo rmr rms rmx rob roe rok rom roo ror ros rox rrb rrk rrm rrr rrs rsb rse rsk rsm rso rsr rss rsx rxr rxs sbb sbe sbk sbm sbo sbr sbs sbx se- seb see sek sem seo ser ses sex sk- skb ske skk skm sko skr sks skx smb sme smk smm smo smr sms smx sob soe sok som soo sor sos sox sr- srb sre srk srm sro srr srs srx ss- ssb sse ssk ssm sso ssr sss ssx sxm sxs xbe xbr xbx xee xem xer xes xex xkb xke xks xmk xmm xmo xmr xms xmx xok xom xoo xor xos xox xrx xsb xsm xss xxo xxx