c-- ccc ccf cco ccs ccu cfc cff cfo cfs cfu co- coc cof coo cos cou csc csf cso css csu cuc cuf cuo cus cuu fcc fcf fco fcs fcu ffc fff ffo ffs ffu foc fof foo fos fou fsc fsf fso fss fsu fuf fuo fus fuu oc- occ ocf oco ocs ocu of- ofc off ofo ofs ofu oo- ooc oof ooo oos os- osc osf oso oss osu ou- ouc ouf ouo ous scc scf sco scs scu sfc sff sfo sfs sfu soc sof soo sos sou ss- ssc ssf sso sss ssu suc suf suo sus suu ucc ucf uco ucs ucu ufc uff ufo ufs ufu uoc uoo uos usc usf uso uss usu uuc uus uuu