b-p bbb bbo bbp bbs bbt bob boo bop bos bot bpb bpo bpp bps bpt bsb bso bsp bss bst btb bto btp bts btt ob- obb obo obp obs obt oo- oob ooo oop oos oot op- opb opo opp ops opt os- osb oso osp oss ost ot- otb oto otp ots ott p-p pbb pbo pbp pbs pbt pob poo pop pos pot ppb ppo ppp pps ppt ps- psb pso psp pss pst pt- ptb pto ptp pts ptt sbb sbo sbp sbs sbt sob soo sop sos sot spb spo spp sps spt ss- ssb sso ssp sss sst stb sto stp sts stt tbb tbo tbp tbs tbt to- tob too top tos tot tpb tpo tpp tps tpt tsb tso tsp tss tst ttb tto ttp tts ttt