b-u bbb bbo bbs bbt bbu bbx bob boo bos bot bou box bsb bso bss bst bsu bsx btb bto bts btt btu btx bub buo bus but buu bux bxb bxo bxx ob- obb obo obs obt obu obx oo- oob ooo oos oot oox os- osb oso oss ost osu osx ot- otb oto ots ott otu ou- ouo ous out ox- oxb oxo oxt oxx sbb sbo sbs sbt sbu sbx sob soo sos sot sou sox ss- ssb sso sss sst ssu ssx stb sto sts stt stu stx sub suo sus sut suu sux sxs sxt sxu t-x tbb tbo tbs tbt tbu to- tob too tos tot tou tox tsb tso tss tst tsu tsx ttb tto tts ttt ttu ttx tub tuo tus tut tuu tux txs txt txu ubb ubo ubs ubt ubu ubx uob uoo uos uot uox usb uso uss ust usu usx utb uto uts utt utu utx uus uut uuu uxb uxo uxt uxu xbx xoo xos xot xox xsb xss xst xts xtx xus xxo xxx