b-u bbb bbn bbs bbt bbu bnb bnn bns bnt bnu bsb bsn bss bst bsu btb btn bts btt btu bub bun bus but buu nbb nbn nbs nbt nbu nnb nnn nns nnt nnu nsb nsn nss nst nsu ntb ntn nts ntt ntu nub nun nus nut nuu sbb sbn sbs sbt sbu snb snn sns snt snu ss- ssb ssn sss sst ssu stb stn sts stt stu sub sun sus sut suu tbb tbn tbs tbt tbu tnb tnn tns tnt tsb tsn tss tst tsu ttb ttn tts ttt ttu tub tun tus tut tuu ubb ubn ubs ubt ubu un- unb unn uns unt unu usb usn uss ust usu utb utn uts utt utu uun uus uut uuu