c-- ccc cce ccf ccm ccs ce- cec cee cef cem ces cfc cfe cff cfm cfs cmc cme cmf cmm cms csc cse csf csm css ec- ecc ece ecf ecm ecs eec eee eef eem ees ef- efc efe eff efm efs em- emc eme emf emm ems es- esc ese esf esm ess fcc fce fcf fcm fcs fec fee fef fem fes ffc ffe fff ffm ffs fmc fme fmf fmm fms fsc fse fsf fsm fss m-f mc- mcc mce mcf mcm mcs mec mee mef mem mes mfc mfe mff mfm mfs mmc mme mmf mmm mms msc mse msf msm mss scc sce scf scm scs se- sec see sef sem ses sfc sfe sff sfm sfs smc sme smf smm sms ss- ssc sse ssf ssm sss