bbb bbc bbn bbo bbr bbt bcb bcc bcn bco bcr bct bnb bnc bnn bno bnr bnt bob boc bon boo bor bot brb brn bro brr brt btb btc btn bto btr btt c-- cbb cbc cbn cbo cbr cbt ccb ccc ccn cco ccr cct cn- cnb cnc cnn cno cnr cnt co- cob coc con coo cor cot crb crc crn cro crr crt ctb ctc ctn cto ctr ctt nbb nbc nbn nbo nbr nbt ncb ncc ncn nco ncr nct nnb nnc nnn nno nnt no- nob noc non noo nor not nrb nrc nrn nro nrr nrt ntb ntc ntn nto ntr ntt ob- obb obc obn obo obr obt oc- ocb occ ocn oco ocr oct on- onb onc onn ono onr ont oo- oob ooc oon ooo oor oot or- orb orc orn oro orr ort ot- otb otc otn oto otr ott rbb rbc rbn rbo rbr rbt rcb rcc rcn rco rcr rct rnb rnc rnn rno rnr rnt rob roc ron roo ror rot rrb rrc rrn rrr rrt rtb rtc rtn rto rtr rtt tbb tbc tbn tbo tbr tbt tcb tcc tcn tco tcr tct tnb tnc tnn tno tnr tnt to- tob toc ton too tor tot trb trc trn tro trr trt ttb ttc ttn tto ttr ttt