bbb bbe bbk bbo bbs bbt be- beb bee bek beo bes bet bkb bke bkk bko bks bkt bob boe bok boo bos bot bsb bse bsk bso bss bst btb bte btk bto bts btt ebb ebe ebk ebo ebs ebt eeb eee eek eeo ees eet ekb eke eko eks ekt eo- eob eoe eok eoo eos eot es- esb ese esk eso ess est etb ete etk eto ets ett k-t kbb kbe kbk kbo kbs ke- keb kee kek keo kes ket kkb kke kkk kks kkt kob koe kok koo kos kot ksb kse ksk kso kss kst ktb kte ktk kto kts ktt ob- obb obe obk obo obs obt oeb oee oeo oes oet okb oke okk oko oks oo- oob ook ooo oos oot os- osb ose osk oso oss ost ot- otb ote otk oto ots ott sbb sbe sbk sbo sbs sbt se- seb see sek seo ses set sk- skb ske skk sko sks skt sob soe sok soo sos sot ss- ssb sse ssk sso sss sst stb ste stk sto sts stt tbb tbe tbk tbo tbs tbt te- teb tee tek teo tes tet tkb tke tkk tko tks tkt to- tob toe tok too tos tot tsb tse tsk tso tss tst ttb tte ttk tto tts ttt