c-- ccc ccd cco ccr ccu cdc cdd cdo cdr cdu co- coc cod coo cor cou crc crd cro crr cru cuc cud cuo cur cuu dcc dcd dco dcr dcu ddc ddd ddo ddr ddu doc dod doo dor dou drc drd dro drr dru duc dud duo dur oc- occ ocd oco ocr ocu odc odd odo odr odu oo- ooc ood ooo oor or- orc ord oro orr oru ou- ouc oud ouo our rcc rcd rco rcr rcu rdc rdd rdo rdr rdu roc rod roo ror rou rrc rrd rrr rru ruc rud ruo rur ruu ucc ucd uco ucr ucu udc udd udo udr udu uoc uod uoo uor ur- urc urd uro urr uru uuc uur uuu