b-u bbb bbs bbt bbu bsb bss bst bsu bsv btb bts btt btu btv bub bus but buu bvb bvs bvt bvu bvv sbb sbs sbt sbu sbv ss- ssb sss sst ssu ssv stb sts stt stu stv sub sus sut suu suv svb svs svt svu svv tbb tbs tbt tbu tbv tsb tss tst tsu tsv ttb tts ttt ttu ttv tub tus tut tuu tuv tvb tvs tvt tvu ubb ubs ubt ubu ubv usb uss ust usu usv utb uts utt utu utv uus uut uuu uvb uvs uvu uvv vbs vbv vsb vss vst vsu vsv vtb vts vtt vtu vtv vus vut vuv vvb vvs vvt vvv