-er a-a a-b a-c aaa aab aac aae aam aar aas ab- aba abb abc abe abm abr abs ac- aca acb acc ace acm acr acs aea aeb aec aee aem aer aes ama amb amc ame amm amr ams ar- ara arb arc are arm arr ars as- asa asb asc ase asm asr ass baa bab bac bae bam bar bas bba bbb bbc bbe bbm bbr bbs bca bcb bcc bce bcm bcr bcs be- bea beb bec bee bem ber bes bma bmb bmc bme bmm bmr bms bra brb bre brm brr brs bsa bsb bsc bse bsm bsr bss c-- caa cab cac cae cam car cas cba cbb cbc cbe cbm cbr cbs cca ccb ccc cce ccm ccr ccs ce- cea ceb cec cee cem cer ces cma cmb cmc cme cmm cmr cms cra crb crc cre crm crr crs csa csb csc cse csm csr css eaa eab eac eae eam ear eas eba ebb ebc ebe ebm ebr ebs ec- eca ecb ecc ece ecm ecr ecs eea eeb eec eee eem eer ees em- ema emb emc eme emm emr ems era erb erc ere erm err ers es- esa esb esc ese esm esr ess m-r maa mab mac mae mam mar mas mba mbb mbc mbe mbm mbr mbs mc- mca mcb mcc mce mcm mcr mcs mea meb mec mee mem mer mes mma mmb mmc mme mmm mmr mms mra mrb mrc mre mrm mrr mrs msa msb msc mse msm msr mss ra- raa rab rac rae ram rar ras rba rbb rbc rbe rbm rbr rbs rca rcb rcc rce rcm rcr rcs re- rea reb rec ree rem rer res rma rmb rmc rme rmm rmr rms rra rrb rrc rrm rrr rrs rsa rsb rsc rse rsm rsr rss saa sab sac sae sam sar sas sba sbb sbc sbe sbm sbr sbs sca scb scc sce scm scr scs se- sea seb sec see sem ser ses sma smb smc sme smm smr sms sr- sra srb src sre srm srr srs ss- ssa ssb ssc sse ssm ssr sss