-er a-a a-b a-c aaa aab aac aae aam aan aar ab- aba abb abc abe abm abn abr ac- aca acb acc ace acm acn acr aea aeb aec aee aem aen aer ama amb amc ame amm amn amr an- ana anb anc ane anm ann anr ar- ara arb arc are arm arn arr baa bab bac bae bam ban bar bba bbb bbc bbe bbm bbn bbr bca bcb bcc bce bcm bcn bcr be- bea beb bec bee bem ben ber bma bmb bmc bme bmm bmn bmr bna bnb bnc bne bnn bnr bra brb bre brm brn brr c-- caa cab cac cae cam can car cba cbb cbc cbe cbm cbn cbr cca ccb ccc cce ccm ccn ccr ce- cea ceb cec cee cem cen cer cma cmb cmc cme cmm cmn cmr cn- cna cnb cnc cne cnm cnn cnr cra crb crc cre crm crn crr eaa eab eac eae eam ean ear eba ebb ebc ebe ebm ebn ebr ec- eca ecb ecc ece ecm ecn ecr eea eeb eec eee eem een eer em- ema emb emc eme emm emn emr en- ena enb enc ene enm enn enr era erb erc ere erm ern err m-r maa mab mac mae mam man mar mba mbb mbc mbe mbm mbr mc- mca mcb mcc mce mcm mcn mcr mea meb mec mee mem men mer mma mmb mmc mme mmm mmn mmr mna mnb mnc mne mnm mnn mnr mra mrb mrc mre mrm mrn mrr naa nab nac nae nam nan nar nba nbb nbc nbe nbm nbn nbr nca ncb ncc nce ncm ncn ncr ne- nea neb nec nee nem nen ner nma nmb nmc nme nmm nmn nmr nna nnb nnc nne nnm nnn nra nrb nrc nre nrm nrn nrr ra- raa rab rac rae ram ran rar rba rbb rbc rbe rbm rbn rbr rca rcb rcc rce rcm rcn rcr re- rea reb rec ree rem ren rer rma rmb rmc rme rmm rmn rmr rna rnb rnc rnm rnn rnr rra rrb rrc rrm rrn rrr