-er b-p bbb bbe bbf bbg bbk bbo bbp bbr bbs be- beb bee bef beg bek beo bep ber bes bfb bfe bff bfg bfo bfp bfr bfs bgb bge bgf bgg bgk bgo bgp bgr bgs bkb bke bkf bkg bkk bko bkp bkr bks bob boe bof bog bok boo bop bor bos bpb bpe bpf bpg bpo bpp bpr bps brb bre brf brg brk bro brp brr brs bsb bse bsf bsg bsk bso bsp bsr bss ebb ebe ebf ebg ebk ebo ebp ebr ebs eeb eee eef eeg eek eeo eep eer ees ef- efb efe eff efg efo efp efr efs egb ege egf egg ego egp egr egs ekb eke ekf ekg eko ekp ekr eks eo- eob eoe eof eog eok eoo eop eor eos ep- epb epe epf epg epo epp epr eps erb ere erf erg erk ero erp err ers es- esb ese esf esg esk eso esp esr ess fbb fbe fbf fbg fbk fbo fbp fbr fbs feb fee fef feg fek feo fep fer fes ffe fff ffg ffk ffo ffp ffr ffs fgb fge fgf fgg fgp fgr fgs fkb fkf fkg fkk fkp fob foe fof fog fok foo fop for fos fpb fpe fpg fpk fpo fpp fpr fps frb fre frf frg frk fro frp frr frs fsb fse fsf fsg fsk fso fsp fsr fss g-p gbe gbf gbg gbk gbo gbp gbr gbs ge- geb gee gef geg gek geo gep ger ges gfb gfe gff gfk gfo gfp gfr gfs ggb ggg ggo ggp ggr ggs gkb gko gkp gks gob goe gof gog gok goo gop gor gos gpb gpe gpf gpg gpk gpo gpp gpr gps grb gre grf grg grk gro grp grr grs gsb gse gsf gsg gsk gso gsp gsr gss kbb kbe kbf kbk kbo kbp kbr kbs ke- keb kee kef keg kek keo kep ker kes kff kfg kfo kfs kgb kgf kgo kgp kgs kkb kke kkk kkp kkr kks kob koe kof kog kok koo kop kor kos kpe kpf kpk kpo kpp kpr kps krf krg krk kro krp krr krs ksb kse ksf ksg ksk kso ksp ksr kss ob- obb obe obf obg obk obo obp obr obs oeb oee oef oeg oeo oep oer oes of- ofb ofe off ofg ofo ofp ofr ofs oge ogf ogg ogo ogp ogs okb oke okg okk oko okp okr oks oo- oob oof oog ook ooo oop oor oos op- opb ope opf opg opk opo opp opr ops or- orb ore orf org ork oro orp orr ors os- osb ose osf osg osk oso osp osr oss p-p pbb pbe pbf pbg pbk pbo pbp pbr pbs peb pee pef peg pek peo pep per pes pfb pfe pff pfg pfk pfo pfp pfr pfs pgb pge pgf pgg pgk pgo pgp pgr pgs pkb pke pkf pkg pko pkp pkr pks pob poe pof pog pok poo pop por pos ppb ppe ppf ppg ppk ppo ppp ppr pps prb pre prf prg prk pro prp prr prs ps- psb pse psf psg psk pso psp psr pss rbb rbe rbf rbg rbk rbo rbp rbr rbs re- reb ree ref reg rek reo rep rer res rfb rfe rff rfg rfk rfo rfp rfr rfs rgb rge rgf rgg rgk rgo rgp rgr rgs rkb rke rkf rkg rkk rko rkp rks rob roe rof rog rok roo rop ror ros rpb rpe rpf rpg rpk rpo rpp rpr rps rrb rrf rrg rrk rrp rrr rrs rsb rse rsf rsg rsk rso rsp rsr rss sbb sbe sbf sbg sbk sbo sbp sbr sbs se- seb see sef seg sek seo sep ser ses sfb sfe sff sfg sfk sfo sfp sfr sfs sgb sge sgf sgg sgk sgo sgp sgr sgs sk- skb ske skf skg skk sko skp skr sks sob soe sof sog sok soo sop sor sos spb spe spf spg spk spo spp spr sps sr- srb sre srf srg srk sro srp srr srs ss- ssb sse ssf ssg ssk sso ssp ssr sss