bbb bbc bbh bbo bbr bcb bcc bch bco bcr bhb bhc bhh bho bhr bob boc boh boo bor brb brh bro brr c-- cbb cbc cbh cbo cbr ccb ccc cch cco ccr ch- chb chc chh cho chr co- cob coc coh coo cor crb crc crh cro crr hbb hbc hbh hbo hbr hcb hcc hch hco hcr hhb hhc hhh hho hhr hob hoc hoh hoo hor hr- hrb hrc hrh hro hrr ob- obb obc obh obo obr oc- ocb occ och oco ocr ohc ohh oho ohr oo- oob ooc ooh ooo oor or- orb orc orh oro orr rbb rbc rbh rbo rbr rcb rcc rch rco rcr rh- rhb rhc rhh rho rhr rob roc roh roo ror rrb rrc rrh rrr