-er c-- ccc cce ccm cco ccr cct ce- cec cee cem ceo cer cet cmc cme cmm cmo cmr cmt co- coc coe com coo cor cot crc cre crm cro crr crt ctc cte ctm cto ctr ctt ec- ecc ece ecm eco ecr ect eec eee eem eeo eer eet em- emc eme emm emo emr emt eo- eoc eoe eom eoo eor eot erc ere erm ero err ert etc ete etm eto etr ett m-o m-r mc- mcc mce mcm mco mcr mct mec mee mem meo mer met mmc mme mmm mmo mmr mmt moc moe mom moo mor mot mrc mre mrm mro mrr mrt mtc mte mtm mto mtr mtt oc- occ ocm oco ocr oct oec oee oem oeo oer oet om- omc ome omm omo omr omt oo- ooc oom ooo oor oot or- orc ore orm oro orr ort ot- otc ote otm oto otr ott rcc rce rcm rco rcr rct re- rec ree rem reo rer ret rmc rme rmm rmo rmr rmt roc roe rom roo ror rot rrc rrm rrr rrt rtc rte rtm rto rtr rtt tcc tce tcm tco tcr tct te- tec tee tem teo ter tet tmc tme tmm tmo tmr tmt to- toc toe tom too tor tot trc tre trm tro trr trt ttc tte ttm tto ttr ttt