-er b-p bbb bbe bbi bbo bbp bbr bbs be- beb bee bei beo bep ber bes bi- bib bie bii bio bip bir bis bob boe boi boo bop bor bos bpb bpe bpi bpo bpp bpr bps brb bre bri bro brp brr brs bsb bse bsi bso bsp bsr bss ebb ebe ebi ebo ebp ebr ebs eeb eee eeo eep eer ees eib eie eii eio eip eir eis eo- eob eoe eoi eoo eop eor eos ep- epb epe epi epo epp epr eps erb ere eri ero erp err ers es- esb ese esi eso esp esr ess ibb ibe ibi ibo ibp ibr ibs ie- iee iei iep ier ies iib iie iii iio iip iir iis io- iob ioe ioi ioo iop ior ios ipb ipe ipi ipo ipp ipr ips ir- irb ire iri iro irp irr irs is- isb ise isi iso isp isr iss o-i ob- obb obe obi obo obp obr obs oeb oee oei oeo oep oer oes oib oie oii oio oip oir ois oo- oob ooi ooo oop oor oos op- opb ope opi opo opp opr ops or- orb ore ori oro orp orr ors os- osb ose osi oso osp osr oss p-p pbb pbe pbi pbo pbp pbr pbs peb pee pei peo pep per pes pib pie pii pio pip pir pis pob poe poi poo pop por pos ppb ppe ppi ppo ppp ppr pps prb pre pri pro prp prr prs ps- psb pse psi pso psp psr pss rbb rbe rbi rbo rbp rbr rbs re- reb ree rei reo rep rer res rib rie rii rio rip rir ris rob roe roi roo rop ror ros rpb rpe rpi rpo rpp rpr rps rrb rri rrp rrr rrs rsb rse rsi rso rsp rsr rss sbb sbe sbi sbo sbp sbr sbs se- seb see sei seo sep ser ses sib sie sii sio sip sir sis sob soe soi soo sop sor sos spb spe spi spo spp spr sps sr- srb sre sri sro srp srr srs ss- ssb sse ssi sso ssp ssr sss