bbb bbn bbo bbs bbt bnb bnn bno bns bnt bob bon boo bos bot bsb bsn bso bss bst btb btn bto bts btt nbb nbn nbo nbs nbt nnb nnn nno nns nnt no- nob non noo nos not nsb nsn nso nss nst ntb ntn nto nts ntt ob- obb obn obo obs obt on- onb onn ono ons ont oo- oob oon ooo oos oot os- osb osn oso oss ost ot- otb otn oto ots ott sbb sbn sbo sbs sbt snb snn sno sns snt sob son soo sos sot ss- ssb ssn sso sss sst stb stn sto sts stt tbb tbn tbo tbs tbt tnb tnn tno tns tnt to- tob ton too tos tot tsb tsn tso tss tst ttb ttn tto tts ttt