-er b-p bbb bbe bbp bbr bbs be- beb bee bep ber bes bpb bpe bpp bpr bps brb bre brp brr brs bsb bse bsp bsr bss ebb ebe ebp ebr ebs eeb eee eep eer ees ep- epb epe epp epr eps erb ere erp err ers es- esb ese esp esr ess p-p pbb pbe pbp pbr pbs peb pee pep per pes ppb ppe ppp ppr pps prb pre prp prr prs ps- psb pse psp psr pss rbb rbe rbp rbr rbs re- reb ree rep rer res rpb rpe rpp rpr rps rrb rrp rrr rrs rsb rse rsp rsr rss sbb sbe sbp sbr sbs se- seb see sep ser ses spb spe spp spr sps sr- srb sre srp srr srs ss- ssb sse ssp ssr sss