-er b-p bbb bbe bbm bbo bbp bbr be- beb bee bem beo bep ber bmb bme bmm bmo bmp bmr bob boe bom boo bop bor bpb bpe bpm bpo bpp bpr brb bre brm bro brp brr ebb ebe ebm ebo ebp ebr eeb eee eem eeo eep eer em- emb eme emm emo emp emr eo- eob eoe eom eoo eop eor ep- epb epe epm epo epp epr erb ere erm ero erp err m-o m-r mbb mbe mbm mbo mbp mbr meb mee mem meo mep mer mmb mme mmm mmo mmp mmr mob moe mom moo mop mor mpb mpe mpm mpo mpp mpr mrb mre mrm mro mrp mrr ob- obb obe obm obo obp obr oeb oee oem oeo oep oer om- omb ome omm omo omp omr oo- oob oom ooo oop oor op- opb ope opm opo opp opr or- orb ore orm oro orp orr p-p pbb pbe pbm pbo pbp pbr peb pee pem peo pep per pmb pme pmm pmo pmp pmr pob poe pom poo pop por ppb ppe ppm ppo ppp ppr prb pre prm pro prp prr rbb rbe rbm rbo rbp rbr re- reb ree rem reo rep rer rmb rme rmm rmo rmp rmr rob roe rom roo rop ror rpb rpe rpm rpo rpp rpr rrb rrm rrp rrr