bbb bbc bbn bbo bbs bbt bcb bcc bcn bco bcs bct bnb bnc bnn bno bns bnt bob boc bon boo bos bot bsb bsc bsn bso bss bst btb btc btn bto bts btt c-- cbb cbc cbn cbo cbs cbt ccb ccc ccn cco ccs cct cn- cnb cnc cnn cno cns cnt co- cob coc con coo cos cot csb csc csn cso css cst ctb ctc ctn cto cts ctt nbb nbc nbn nbo nbs nbt ncb ncc ncn nco ncs nct nnb nnc nnn nno nns nnt no- nob noc non noo nos not nsb nsc nsn nso nss nst ntb ntc ntn nto nts ntt ob- obb obc obn obo obs obt oc- ocb occ ocn oco ocs oct on- onb onc onn ono ons ont oo- oob ooc oon ooo oos oot os- osb osc osn oso oss ost ot- otb otc otn oto ots ott sbb sbc sbn sbo sbs sbt scb scc scn sco scs sct snb snc snn sno sns snt sob soc son soo sos sot ss- ssb ssc ssn sso sss sst stb stc stn sto sts stt tbb tbc tbn tbo tbs tbt tcb tcc tcn tco tcs tct tnb tnc tnn tno tns tnt to- tob toc ton too tos tot tsb tsc tsn tso tss tst ttb ttc ttn tto tts ttt