-er b-p bbb bbe bbi bbp bbr bbs be- beb bee bei bep ber bes bi- bib bie bii bip bir bis bpb bpe bpi bpp bpr bps brb bre bri brp brr brs bsb bse bsi bsp bsr bss ebb ebe ebi ebp ebr ebs eeb eee eep eer ees eib eie eii eip eir eis ep- epb epe epi epp epr eps erb ere eri erp err ers es- esb ese esi esp esr ess ibb ibe ibi ibp ibr ibs ie- iee iei iep ier ies iib iie iii iip iir iis ipb ipe ipi ipp ipr ips ir- irb ire iri irp irr irs is- isb ise isi isp isr iss p-p pbb pbe pbi pbp pbr pbs peb pee pei pep per pes pib pie pii pip pir pis ppb ppe ppi ppp ppr pps prb pre pri prp prr prs ps- psb pse psi psp psr pss rbb rbe rbi rbp rbr rbs re- reb ree rei rep rer res rib rie rii rip rir ris rpb rpe rpi rpp rpr rps rrb rri rrp rrr rrs rsb rse rsi rsp rsr rss sbb sbe sbi sbp sbr sbs se- seb see sei sep ser ses sib sie sii sip sir sis spb spe spi spp spr sps sr- srb sre sri srp srr srs ss- ssb sse ssi ssp ssr sss