b-u bbb bbn bbr bbs bbt bbu bnb bnn bnr bns bnt bnu brb brn brr brs brt bru bsb bsn bsr bss bst bsu btb btn btr bts btt btu bub bun bur bus but buu nbb nbn nbr nbs nbt nbu nnb nnn nns nnt nnu nrb nrn nrr nrs nrt nru nsb nsn nsr nss nst nsu ntb ntn ntr nts ntt ntu nub nun nur nus nut nuu rbb rbn rbr rbs rbt rbu rnb rnn rnr rns rnt rnu rrb rrn rrr rrs rrt rru rsb rsn rsr rss rst rsu rtb rtn rtr rts rtt rtu rub run rur rus rut ruu sbb sbn sbr sbs sbt sbu snb snn snr sns snt snu sr- srb srn srr srs srt ss- ssb ssn ssr sss sst ssu stb stn str sts stt stu sub sun sur sus sut suu tbb tbn tbr tbs tbt tbu tnb tnn tnr tns tnt trb trn trr trs trt tru tsb tsn tsr tss tst tsu ttb ttn ttr tts ttt ttu tub tun tur tus tut tuu ubb ubn ubr ubs ubt ubu un- unb unn unr uns unt unu ur- urb urn urr urs urt uru usb usn usr uss ust usu utb utn utr uts utt utu uun uur uus uut uuu