-er bbb bbe bbf bbo bbr bbs be- beb bee bef beo ber bes bfb bfe bff bfo bfr bfs bob boe bof boo bor bos brb bre brf bro brr brs bsb bse bsf bso bsr bss ebb ebe ebf ebo ebr ebs eeb eee eef eeo eer ees ef- efb efe eff efo efr efs eo- eob eoe eof eoo eor eos erb ere erf ero err ers es- esb ese esf eso esr ess fbb fbe fbf fbo fbr fbs feb fee fef feo fer fes ffe fff ffo ffr ffs fob foe fof foo for fos frb fre frf fro frr frs fsb fse fsf fso fsr fss ob- obb obe obf obo obr obs oeb oee oef oeo oer oes of- ofb ofe off ofo ofr ofs oo- oob oof ooo oor oos or- orb ore orf oro orr ors os- osb ose osf oso osr oss rbb rbe rbf rbo rbr rbs re- reb ree ref reo rer res rfb rfe rff rfo rfr rfs rob roe rof roo ror ros rrb rrf rrr rrs rsb rse rsf rso rsr rss sbb sbe sbf sbo sbr sbs se- seb see sef seo ser ses sfb sfe sff sfo sfr sfs sob soe sof soo sor sos sr- srb sre srf sro srr srs ss- ssb sse ssf sso ssr sss