b-p bbb bbi bbo bbp bbr bbs bbt bi- bib bii bio bip bir bis bit bob boi boo bop bor bos bot bpb bpi bpo bpp bpr bps bpt brb bri bro brp brr brs brt bsb bsi bso bsp bsr bss bst btb bti bto btp btr bts btt ibb ibi ibo ibp ibr ibs ibt iib iii iio iip iir iis iit io- iob ioi ioo iop ior ios iot ipb ipi ipo ipp ipr ips ipt ir- irb iri iro irp irr irs irt is- isb isi iso isp isr iss ist itb iti ito itp its itt o-i ob- obb obi obo obp obr obs obt oib oii oio oip oir ois oit oo- oob ooi ooo oop oor oos oot op- opb opi opo opp opr ops opt or- orb ori oro orp orr ors ort os- osb osi oso osp osr oss ost ot- otb oti oto otp otr ots ott p-p pbb pbi pbo pbp pbr pbs pbt pib pii pio pip pir pis pit pob poi poo pop por pos pot ppb ppi ppo ppp ppr pps ppt prb pri pro prp prr prs prt ps- psb psi pso psp psr pss pst pt- ptb pti pto ptp ptr pts ptt rbb rbi rbo rbp rbr rbs rbt rib rii rio rip rir ris rit rob roi roo rop ror ros rot rpb rpi rpo rpp rpr rps rpt rrb rri rrp rrr rrs rrt rsb rsi rso rsp rsr rss rst rtb rti rto rtp rtr rts rtt sbb sbi sbo sbp sbr sbs sbt sib sii sio sip sir sis sit sob soi soo sop sor sos sot spb spi spo spp spr sps spt sr- srb sri sro srp srr srs srt ss- ssb ssi sso ssp ssr sss sst stb sti sto stp str sts stt tbb tbi tbo tbp tbr tbs tbt tib tii tio tip tir tis tit to- tob toi too top tor tos tot tpb tpi tpo tpp tpr tps tpt trb tri tro trp trr trs trt tsb tsi tso tsp tsr tss tst ttb tti tto ttp ttr tts ttt