c-- ccc cce ccf ccm cco ccs ce- cec cee cef cem ceo ces cfc cfe cff cfm cfo cfs cmc cme cmf cmm cmo cms co- coc coe cof com coo cos csc cse csf csm cso css ec- ecc ece ecf ecm eco ecs eec eee eef eem eeo ees ef- efc efe eff efm efo efs em- emc eme emf emm emo ems eo- eoc eoe eof eom eoo eos es- esc ese esf esm eso ess fcc fce fcf fcm fco fcs fec fee fef fem feo fes ffc ffe fff ffm ffo ffs fmc fme fmf fmm fmo fms foc foe fof fom foo fos fsc fse fsf fsm fso fss m-f m-o mc- mcc mce mcf mcm mco mcs mec mee mef mem meo mes mfc mfe mff mfm mfo mfs mmc mme mmf mmm mmo mms moc moe mof mom moo mos msc mse msf msm mso mss oc- occ ocf ocm oco ocs oec oee oef oem oeo oes of- ofc ofe off ofm ofo ofs om- omc ome omf omm omo oms oo- ooc oof oom ooo oos os- osc ose osf osm oso oss scc sce scf scm sco scs se- sec see sef sem seo ses sfc sfe sff sfm sfo sfs smc sme smf smm smo sms soc soe sof som soo sos ss- ssc sse ssf ssm sso sss