-er b-p bbb bbc bbe bbm bbo bbp bbr bcb bcc bce bcm bco bcp bcr be- beb bec bee bem beo bep ber bmb bmc bme bmm bmo bmp bmr bob boc boe bom boo bop bor bpb bpc bpe bpm bpo bpp bpr brb bre brm bro brp brr c-- cbb cbc cbe cbm cbo cbp cbr ccb ccc cce ccm cco ccp ccr ce- ceb cec cee cem ceo cep cer cmb cmc cme cmm cmo cmp cmr co- cob coc coe com coo cop cor cpb cpc cpe cpm cpo cpp cpr crb crc cre crm cro crp crr ebb ebc ebe ebm ebo ebp ebr ec- ecb ecc ece ecm eco ecr eeb eec eee eem eeo eep eer em- emb emc eme emm emo emp emr eo- eob eoc eoe eom eoo eop eor ep- epb epc epe epm epo epp epr erb erc ere erm ero erp err m-o m-r mbb mbc mbe mbm mbo mbp mbr mc- mcb mcc mce mcm mco mcp mcr meb mec mee mem meo mep mer mmb mmc mme mmm mmo mmp mmr mob moc moe mom moo mop mor mpb mpc mpe mpm mpo mpp mpr mrb mrc mre mrm mro mrp mrr ob- obb obc obe obm obo obp obr oc- ocb occ ocm oco ocp ocr oeb oec oee oem oeo oep oer om- omb omc ome omm omo omp omr oo- oob ooc oom ooo oop oor op- opb opc ope opm opo opp opr or- orb orc ore orm oro orp orr p-p pbb pbc pbe pbm pbo pbp pbr pcb pcc pce pcm pco pcp pcr peb pec pee pem peo pep per pmb pmc pme pmm pmo pmp pmr pob poc poe pom poo pop por ppb ppc ppe ppm ppo ppp ppr prb prc pre prm pro prp prr rbb rbc rbe rbm rbo rbp rbr rcb rcc rce rcm rco rcp rcr re- reb rec ree rem reo rep rer rmb rmc rme rmm rmo rmp rmr rob roc roe rom roo rop ror rpb rpc rpe rpm rpo rpp rpr rrb rrc rrm rrp rrr