b-u bbb bbc bbr bbs bbt bbu bcb bcc bcr bcs bct bcu brb brr brs brt bru bsb bsc bsr bss bst bsu btb btc btr bts btt btu bub buc bur bus but buu c-- cbb cbc cbr cbs cbt cbu ccb ccc ccr ccs cct ccu crb crc crr crs crt cru csb csc csr css cst csu ctb ctc ctr cts ctt ctu cub cuc cur cus cut cuu rbb rbc rbr rbs rbt rbu rcb rcc rcr rcs rct rcu rrb rrc rrr rrs rrt rru rsb rsc rsr rss rst rsu rtb rtc rtr rts rtt rtu rub ruc rur rus rut ruu sbb sbc sbr sbs sbt sbu scb scc scr scs sct scu sr- srb src srr srs srt ss- ssb ssc ssr sss sst ssu stb stc str sts stt stu sub suc sur sus sut suu tbb tbc tbr tbs tbt tbu tcb tcc tcr tcs tct tcu trb trc trr trs trt tru tsb tsc tsr tss tst tsu ttb ttc ttr tts ttt ttu tub tuc tur tus tut tuu ubb ubc ubr ubs ubt ubu ucb ucc ucr ucs uct ucu ur- urb urc urr urs urt uru usb usc usr uss ust usu utb utc utr uts utt utu uuc uur uus uut uuu