-er b-p bbb bbe bbp bbr bbs bbt be- beb bee bep ber bes bet bpb bpe bpp bpr bps bpt brb bre brp brr brs brt bsb bse bsp bsr bss bst btb bte btp btr bts btt ebb ebe ebp ebr ebs ebt eeb eee eep eer ees eet ep- epb epe epp epr eps ept erb ere erp err ers ert es- esb ese esp esr ess est etb ete etp etr ets ett p-p pbb pbe pbp pbr pbs pbt peb pee pep per pes pet ppb ppe ppp ppr pps ppt prb pre prp prr prs prt ps- psb pse psp psr pss pst pt- ptb pte ptp ptr pts ptt rbb rbe rbp rbr rbs rbt re- reb ree rep rer res ret rpb rpe rpp rpr rps rpt rrb rrp rrr rrs rrt rsb rse rsp rsr rss rst rtb rte rtp rtr rts rtt sbb sbe sbp sbr sbs sbt se- seb see sep ser ses set spb spe spp spr sps spt sr- srb sre srp srr srs srt ss- ssb sse ssp ssr sss sst stb ste stp str sts stt tbb tbe tbp tbr tbs tbt te- teb tee tep ter tes tet tpb tpe tpp tpr tps tpt trb tre trp trr trs trt tsb tse tsp tsr tss tst ttb tte ttp ttr tts ttt