b-p bbb bbi bbo bbp bbr bbt bi- bib bii bio bip bir bit bob boi boo bop bor bot bpb bpi bpo bpp bpr bpt brb bri bro brp brr brt btb bti bto btp btr btt ibb ibi ibo ibp ibr ibt iib iii iio iip iir iit io- iob ioi ioo iop ior iot ipb ipi ipo ipp ipr ipt ir- irb iri iro irp irr irt itb iti ito itp itt o-i ob- obb obi obo obp obr obt oib oii oio oip oir oit oo- oob ooi ooo oop oor oot op- opb opi opo opp opr opt or- orb ori oro orp orr ort ot- otb oti oto otp otr ott p-p pbb pbi pbo pbp pbr pbt pib pii pio pip pir pit pob poi poo pop por pot ppb ppi ppo ppp ppr ppt prb pri pro prp prr prt pt- ptb pti pto ptp ptr ptt rbb rbi rbo rbp rbr rbt rib rii rio rip rir rit rob roi roo rop ror rot rpb rpi rpo rpp rpr rpt rrb rri rrp rrr rrt rtb rti rto rtp rtr rtt tbb tbi tbo tbp tbr tbt tib tii tio tip tir tit to- tob toi too top tor tot tpb tpi tpo tpp tpr tpt trb tri tro trp trr trt ttb tti tto ttp ttr ttt