b-p bbb bbi bbp bbr bbs bbt bi- bib bii bip bir bis bit bpb bpi bpp bpr bps bpt brb bri brp brr brs brt bsb bsi bsp bsr bss bst btb bti btp btr bts btt ibb ibi ibp ibr ibs ibt iib iii iip iir iis iit ipb ipi ipp ipr ips ipt ir- irb iri irp irr irs irt is- isb isi isp isr iss ist itb iti itp its itt p-p pbb pbi pbp pbr pbs pbt pib pii pip pir pis pit ppb ppi ppp ppr pps ppt prb pri prp prr prs prt ps- psb psi psp psr pss pst pt- ptb pti ptp ptr pts ptt rbb rbi rbp rbr rbs rbt rib rii rip rir ris rit rpb rpi rpp rpr rps rpt rrb rri rrp rrr rrs rrt rsb rsi rsp rsr rss rst rtb rti rtp rtr rts rtt sbb sbi sbp sbr sbs sbt sib sii sip sir sis sit spb spi spp spr sps spt sr- srb sri srp srr srs srt ss- ssb ssi ssp ssr sss sst stb sti stp str sts stt tbb tbi tbp tbr tbs tbt tib tii tip tir tis tit tpb tpi tpp tpr tps tpt trb tri trp trr trs trt tsb tsi tsp tsr tss tst ttb tti ttp ttr tts ttt