-er b-p bbb bbc bbe bbo bbp bbr bbs bcb bcc bce bco bcp bcr bcs be- beb bec bee beo bep ber bes bob boc boe boo bop bor bos bpb bpc bpe bpo bpp bpr bps brb bre bro brp brr brs bsb bsc bse bso bsp bsr bss c-- cbb cbc cbe cbo cbp cbr cbs ccb ccc cce cco ccp ccr ccs ce- ceb cec cee ceo cep cer ces co- cob coc coe coo cop cor cos cpb cpc cpe cpo cpp cpr cps crb crc cre cro crp crr crs csb csc cse cso csp csr css ebb ebc ebe ebo ebp ebr ebs ec- ecb ecc ece eco ecr ecs eeb eec eee eeo eep eer ees eo- eob eoc eoe eoo eop eor eos ep- epb epc epe epo epp epr eps erb erc ere ero erp err ers es- esb esc ese eso esp esr ess ob- obb obc obe obo obp obr obs oc- ocb occ oco ocp ocr ocs oeb oec oee oeo oep oer oes oo- oob ooc ooo oop oor oos op- opb opc ope opo opp opr ops or- orb orc ore oro orp orr ors os- osb osc ose oso osp osr oss p-p pbb pbc pbe pbo pbp pbr pbs pcb pcc pce pco pcp pcr pcs peb pec pee peo pep per pes pob poc poe poo pop por pos ppb ppc ppe ppo ppp ppr pps prb prc pre pro prp prr prs ps- psb psc pse pso psp psr pss rbb rbc rbe rbo rbp rbr rbs rcb rcc rce rco rcp rcr rcs re- reb rec ree reo rep rer res rob roc roe roo rop ror ros rpb rpc rpe rpo rpp rpr rps rrb rrc rrp rrr rrs rsb rsc rse rso rsp rsr rss sbb sbc sbe sbo sbp sbr sbs scb scc sce sco scp scr scs se- seb sec see seo sep ser ses sob soc soe soo sop sor sos spb spc spe spo spp spr sps sr- srb src sre sro srp srr srs ss- ssb ssc sse sso ssp ssr sss