-er b-p bbb bbe bbn bbo bbp bbr bbs be- beb bee ben beo bep ber bes bnb bne bnn bno bnp bnr bns bob boe bon boo bop bor bos bpb bpe bpn bpo bpp bpr bps brb bre brn bro brp brr brs bsb bse bsn bso bsp bsr bss ebb ebe ebn ebo ebp ebr ebs eeb eee een eeo eep eer ees en- enb ene enn eno enp enr ens eo- eob eoe eon eoo eop eor eos ep- epb epe epn epo epp epr eps erb ere ern ero erp err ers es- esb ese esn eso esp esr ess nbb nbe nbn nbo nbp nbr nbs ne- neb nee nen neo nep ner nes nnb nne nnn nno nnp nns no- nob noe non noo nop nor nos npb npe npn npo npp npr nps nrb nre nrn nro nrp nrr nrs nsb nse nsn nso nsp nsr nss ob- obb obe obn obo obp obr obs oeb oee oen oeo oep oer oes on- onb one onn ono onp onr ons oo- oob oon ooo oop oor oos op- opb ope opn opo opp opr ops or- orb ore orn oro orp orr ors os- osb ose osn oso osp osr oss p-p pbb pbe pbn pbo pbp pbr pbs peb pee pen peo pep per pes pn- pnb pne pnn pno pnp pnr pns pob poe pon poo pop por pos ppb ppe ppn ppo ppp ppr pps prb pre prn pro prp prr prs ps- psb pse psn pso psp psr pss rbb rbe rbn rbo rbp rbr rbs re- reb ree ren reo rep rer res rnb rnn rno rnp rnr rns rob roe ron roo rop ror ros rpb rpe rpn rpo rpp rpr rps rrb rrn rrp rrr rrs rsb rse rsn rso rsp rsr rss sbb sbe sbn sbo sbp sbr sbs se- seb see sen seo sep ser ses snb sne snn sno snp snr sns sob soe son soo sop sor sos spb spe spn spo spp spr sps sr- srb sre srn sro srp srr srs ss- ssb sse ssn sso ssp ssr sss