-er a-a a-b a-c aaa aab aac aad aae aaf aar ab- aba abb abc abd abe abf abr ac- aca acb acc acd ace acf acr ad- ada adb adc add ade adf adr aea aeb aec aed aee aef aer af- afa afb afc afd afe aff afr ar- ara arb arc ard are arf arr baa bab bac bad bae baf bar bba bbb bbc bbd bbe bbf bbr bca bcb bcc bcd bce bcf bcr bda bdb bdc bdd bde bdf bdr be- bea beb bec bed bee bef ber bfa bfb bfc bfd bfe bff bfr bra brb brd bre brf brr c-- caa cab cac cad cae caf car cba cbb cbc cbd cbe cbf cbr cca ccb ccc ccd cce ccf ccr cda cdb cdc cdd cde cdf cdr ce- cea ceb cec ced cee cef cer cfa cfb cfc cfd cfe cff cfr cra crb crc crd cre crf crr daa dab dac dad dae daf dar dba dbb dbc dbd dbe dbf dbr dca dcb dcc dcd dce dcf dcr dda ddb ddc ddd dde ddf ddr de- dea deb dec ded dee def der dfa dfb dfc dfd dfe dff dfr dra drb drc drd dre drr eaa eab eac ead eae eaf ear eba ebb ebc ebd ebe ebf ebr ec- eca ecb ecc ecd ece ecf ecr ed- eda edb edc edd ede edf edr eea eeb eec eed eee eef eer ef- efa efb efc efd efe eff efr era erb erc erd ere erf err faa fab fac fad fae faf far fba fbb fbc fbd fbe fbf fbr fca fcb fcc fcd fce fcf fcr fda fdb fdc fdd fde fdf fdr fea feb fec fed fee fef fer ffa ffc ffd ffe fff ffr fra frb frc frd fre frf frr ra- raa rab rac rad rae raf rar rba rbb rbc rbd rbe rbf rbr rca rcb rcc rcd rce rcf rcr rda rdb rdc rdd rde rdf rdr re- rea reb rec red ree ref rer rfa rfb rfc rfd rfe rff rfr rra rrb rrc rrd rrf rrr