b-p bbb bbe bbo bbp bbs bbt be- beb bee beo bep bes bet bob boe boo bop bos bot bpb bpe bpo bpp bps bpt bsb bse bso bsp bss bst btb bte bto btp bts btt ebb ebe ebo ebp ebs ebt eeb eee eeo eep ees eet eo- eob eoe eoo eop eos eot ep- epb epe epo epp eps ept es- esb ese eso esp ess est etb ete eto etp ets ett ob- obb obe obo obp obs obt oeb oee oeo oep oes oet oo- oob ooo oop oos oot op- opb ope opo opp ops opt os- osb ose oso osp oss ost ot- otb ote oto otp ots ott p-p pbb pbe pbo pbp pbs pbt peb pee peo pep pes pet pob poe poo pop pos pot ppb ppe ppo ppp pps ppt ps- psb pse pso psp pss pst pt- ptb pte pto ptp pts ptt sbb sbe sbo sbp sbs sbt se- seb see seo sep ses set sob soe soo sop sos sot spb spe spo spp sps spt ss- ssb sse sso ssp sss sst stb ste sto stp sts stt tbb tbe tbo tbp tbs tbt te- teb tee teo tep tes tet to- tob toe too top tos tot tpb tpe tpo tpp tps tpt tsb tse tso tsp tss tst ttb tte tto ttp tts ttt