-er a-a a-b a-c aaa aab aac aad aae aaf aak aar ab- aba abb abc abd abe abf abk abr ac- aca acb acc acd ace acf ack acr ad- ada adb adc add ade adf adk adr aea aeb aec aed aee aef aek aer af- afa afb afc afd afe aff afk afr aka akb akc akd ake akk akr ar- ara arb arc ard are arf ark arr baa bab bac bad bae baf bak bar bba bbb bbc bbd bbe bbf bbk bbr bca bcb bcc bcd bce bcf bck bcr bda bdb bdc bdd bde bdf bdk bdr be- bea beb bec bed bee bef bek ber bfa bfb bfc bfd bfe bff bfr bka bkb bkc bke bkf bkk bkr bra brb brd bre brf brk brr c-- caa cab cac cad cae caf cak car cba cbb cbc cbd cbe cbf cbk cbr cca ccb ccc ccd cce ccf cck ccr cda cdb cdc cdd cde cdf cdk cdr ce- cea ceb cec ced cee cef cek cer cfa cfb cfc cfd cfe cff cfk cfr cka ckb ckc ckd cra crb crc crd cre crf crk crr daa dab dac dad dae daf dak dar dba dbb dbc dbd dbe dbf dbk dbr dca dcb dcc dcd dce dcf dck dcr dda ddb ddc ddd dde ddf ddk ddr de- dea deb dec ded dee def dek der dfa dfb dfc dfd dfe dff dfk dfr dka dkb dkc dke dkk dkr dra drb drc drd dre drk drr eaa eab eac ead eae eaf eak ear eba ebb ebc ebd ebe ebf ebk ebr ec- eca ecb ecc ecd ece ecf eck ecr ed- eda edb edc edd ede edf edk edr eea eeb eec eed eee eef eek eer ef- efa efb efc efd efe eff efr eka ekb ekc ekd eke ekf ekr era erb erc erd ere erf erk err faa fab fac fad fae faf fak far fba fbb fbc fbd fbe fbf fbk fbr fca fcb fcc fcd fce fcf fck fcr fda fdb fdc fdd fde fdf fdk fdr fea feb fec fed fee fef fek fer ffa ffc ffd ffe fff ffk ffr fka fkb fkc fkf fkk fra frb frc frd fre frf frk frr ka- kaa kab kac kad kae kaf kak kar kba kbb kbc kbd kbe kbf kbk kbr kca kcb kcc kcd kce kck kcr kda kdb kdc kde kdf kdk kdr ke- kea keb kec ked kee kef kek ker kfa kfc kfd kff kkb kkc kke kkk kkr kra krc krd krf krk krr ra- raa rab rac rad rae raf rak rar rba rbb rbc rbd rbe rbf rbk rbr rca rcb rcc rcd rce rcf rcr rda rdb rdc rdd rde rdf rdr re- rea reb rec red ree ref rek rer rfa rfb rfc rfd rfe rff rfk rfr rkb rkc rke rkf rkk rra rrb rrc rrd rrf rrk rrr