-er c-- ccc cce ccf ccl ccr ccs ce- cec cee cef cel cer ces cfc cfe cff cfl cfr cfs cl- clc cle clf cll clr cls crc cre crf crl crr crs csc cse csf csl csr css ec- ecc ece ecf ecl ecr ecs eec eee eef eel eer ees ef- efc efe eff efl efr efs elc ele elf ell elr els erc ere erf erl err ers es- esc ese esf esl esr ess fcc fce fcf fcl fcr fcs fec fee fef fel fer fes ffc ffe fff ffl ffr ffs flc fle flf fll flr fls frc fre frf frl frr frs fsc fse fsf fsl fsr fss lcc lce lcf lcl lcr lcs lec lee lef lel ler les lfc lfe lff lfl lfr lfs llc lle llf lll llr lls lrc lrf lrr lrs lsc lse lsf lsl lsr lss rcc rce rcf rcl rcr rcs re- rec ree ref rel rer res rfc rfe rff rfl rfr rfs rlc rle rlf rll rlr rls rrc rrf rrl rrr rrs rsc rse rsf rsl rsr rss scc sce scf scl scr scs se- sec see sef sel ser ses sfc sfe sff sfl sfr sfs slc sle slf sll slr sls sr- src sre srf srl srr srs ss- ssc sse ssf ssl ssr sss