-er a-a a-b a-c aaa aab aac aad aae aar aas ab- aba abb abc abd abe abr abs ac- aca acb acc acd ace acr acs ad- ada adb adc add ade adr ads aea aeb aec aed aee aer aes ar- ara arb arc ard are arr ars as- asa asb asc asd ase asr ass baa bab bac bad bae bar bas bba bbb bbc bbd bbe bbr bbs bca bcb bcc bcd bce bcr bcs bda bdb bdc bdd bde bdr bds be- bea beb bec bed bee ber bes bra brb brd bre brr brs bsa bsb bsc bsd bse bsr bss c-- caa cab cac cad cae car cas cba cbb cbc cbd cbe cbr cbs cca ccb ccc ccd cce ccr ccs cda cdb cdc cdd cde cdr cds ce- cea ceb cec ced cee cer ces cra crb crc crd cre crr crs csa csb csc csd cse csr css daa dab dac dad dae dar das dba dbb dbc dbd dbe dbr dbs dca dcb dcc dcd dce dcr dcs dda ddb ddc ddd dde ddr dds de- dea deb dec ded dee der des dra drb drc drd dre drr drs dsa dsb dsc dsd dse dsr dss eaa eab eac ead eae ear eas eba ebb ebc ebd ebe ebr ebs ec- eca ecb ecc ecd ece ecr ecs ed- eda edb edc edd ede edr eds eea eeb eec eed eee eer ees era erb erc erd ere err ers es- esa esb esc esd ese esr ess ra- raa rab rac rad rae rar ras rba rbb rbc rbd rbe rbr rbs rca rcb rcc rcd rce rcr rcs rda rdb rdc rdd rde rdr rds re- rea reb rec red ree rer res rra rrb rrc rrd rrr rrs rsa rsb rsc rsd rse rsr rss saa sab sac sad sae sar sas sba sbb sbc sbd sbe sbr sbs sca scb scc scd sce scr scs sda sdb sdc sdd sde sdr sds se- sea seb sec sed see ser ses sr- sra srb src srd sre srr srs ss- ssa ssb ssc ssd sse ssr sss