bbb bbc bbk bbs bbt bcb bcc bck bcs bct bkb bkc bkk bks bkt bsb bsc bsk bss bst btb btc btk bts btt c-- cbb cbc cbk cbs cbt ccb ccc cck ccs cct ckb ckc cks ckt csb csc csk css cst ctb ctc ctk cts ctt k-t kbb kbc kbk kbs kcb kcc kck kcs kct kkb kkc kkk kks kkt ksb ksc ksk kss kst ktb ktc ktk kts ktt sbb sbc sbk sbs sbt scb scc sck scs sct sk- skb skc skk sks skt ss- ssb ssc ssk sss sst stb stc stk sts stt tbb tbc tbk tbs tbt tcb tcc tck tcs tct tkb tkc tkk tks tkt tsb tsc tsk tss tst ttb ttc ttk tts ttt