-er a-a a-b a-c aaa aab aac aad aae aar ab- aba abb abc abd abe abr ac- aca acb acc acd ace acr ad- ada adb adc add ade adr aea aeb aec aed aee aer ar- ara arb arc ard are arr baa bab bac bad bae bar bba bbb bbc bbd bbe bbr bca bcb bcc bcd bce bcr bda bdb bdc bdd bde bdr be- bea beb bec bed bee ber bra brb brd bre brr c-- caa cab cac cad cae car cba cbb cbc cbd cbe cbr cca ccb ccc ccd cce ccr cda cdb cdc cdd cde cdr ce- cea ceb cec ced cee cer cra crb crc crd cre crr daa dab dac dad dae dar dba dbb dbc dbd dbe dbr dca dcb dcc dcd dce dcr dda ddb ddc ddd dde ddr de- dea deb dec ded dee der dra drb drc drd dre drr eaa eab eac ead eae ear eba ebb ebc ebd ebe ebr ec- eca ecb ecc ecd ece ecr ed- eda edb edc edd ede edr eea eeb eec eed eee eer era erb erc erd ere err ra- raa rab rac rad rae rar rba rbb rbc rbd rbe rbr rca rcb rcc rcd rce rcr rda rdb rdc rdd rde rdr re- rea reb rec red ree rer rra rrb rrc rrd rrr