-er a-a a-b a-c aaa aab aac aad aae aak aar ab- aba abb abc abd abe abk abr ac- aca acb acc acd ace ack acr ad- ada adb adc add ade adk adr aea aeb aec aed aee aek aer aka akb akc akd ake akk akr ar- ara arb arc ard are ark arr baa bab bac bad bae bak bar bba bbb bbc bbd bbe bbk bbr bca bcb bcc bcd bce bck bcr bda bdb bdc bdd bde bdk bdr be- bea beb bec bed bee bek ber bka bkb bkc bke bkk bkr bra brb brd bre brk brr c-- caa cab cac cad cae cak car cba cbb cbc cbd cbe cbk cbr cca ccb ccc ccd cce cck ccr cda cdb cdc cdd cde cdk cdr ce- cea ceb cec ced cee cek cer cka ckb ckc ckd cra crb crc crd cre crk crr daa dab dac dad dae dak dar dba dbb dbc dbd dbe dbk dbr dca dcb dcc dcd dce dck dcr dda ddb ddc ddd dde ddk ddr de- dea deb dec ded dee dek der dka dkb dkc dke dkk dkr dra drb drc drd dre drk drr eaa eab eac ead eae eak ear eba ebb ebc ebd ebe ebk ebr ec- eca ecb ecc ecd ece eck ecr ed- eda edb edc edd ede edk edr eea eeb eec eed eee eek eer eka ekb ekc ekd eke ekr era erb erc erd ere erk err ka- kaa kab kac kad kae kak kar kba kbb kbc kbd kbe kbk kbr kca kcb kcc kcd kce kck kcr kda kdb kdc kde kdk kdr ke- kea keb kec ked kee kek ker kkb kkc kke kkk kkr kra krc krd krk krr ra- raa rab rac rad rae rak rar rba rbb rbc rbd rbe rbk rbr rca rcb rcc rcd rce rcr rda rdb rdc rdd rde rdr re- rea reb rec red ree rek rer rkb rkc rke rkk rra rrb rrc rrd rrk rrr