b-p bbb bbi bbo bbp bbs bi- bib bii bio bip bis bob boi boo bop bos bpb bpi bpo bpp bps bsb bsi bso bsp bss ibb ibi ibo ibp ibs iib iii iio iip iis io- iob ioi ioo iop ios ipb ipi ipo ipp ips is- isb isi iso isp iss o-i ob- obb obi obo obp obs oib oii oio oip ois oo- oob ooi ooo oop oos op- opb opi opo opp ops os- osb osi oso osp oss p-p pbb pbi pbo pbp pbs pib pii pio pip pis pob poi poo pop pos ppb ppi ppo ppp pps ps- psb psi pso psp pss sbb sbi sbo sbp sbs sib sii sio sip sis sob soi soo sop sos spb spi spo spp sps ss- ssb ssi sso ssp sss