-er a-a a-b a-c aaa aab aac aad aae aaf aao aar ab- aba abb abc abd abe abf abo abr ac- aca acb acc acd ace acf aco acr ad- ada adb adc add ade adf ado adr aea aeb aec aed aee aef aeo aer af- afa afb afc afd afe aff afo afr aoa aob aoc aod aoe aof aoo aor ar- ara arb arc ard are arf aro arr baa bab bac bad bae baf bao bar bba bbb bbc bbd bbe bbf bbo bbr bca bcb bcc bcd bce bcf bco bcr bda bdb bdc bdd bde bdf bdo bdr be- bea beb bec bed bee bef beo ber bfa bfb bfc bfd bfe bff bfo bfr boa bob boc bod boe bof boo bor bra brb brd bre brf bro brr c-- caa cab cac cad cae caf cao car cba cbb cbc cbd cbe cbf cbo cbr cca ccb ccc ccd cce ccf cco ccr cda cdb cdc cdd cde cdf cdo cdr ce- cea ceb cec ced cee cef ceo cer cfa cfb cfc cfd cfe cff cfo cfr co- coa cob coc cod coe cof coo cor cra crb crc crd cre crf cro crr daa dab dac dad dae daf dao dar dba dbb dbc dbd dbe dbf dbo dbr dca dcb dcc dcd dce dcf dco dcr dda ddb ddc ddd dde ddf ddo ddr de- dea deb dec ded dee def deo der dfa dfb dfc dfd dfe dff dfo dfr doa dob doc dod doe dof doo dor dra drb drc drd dre dro drr eaa eab eac ead eae eaf eao ear eba ebb ebc ebd ebe ebf ebo ebr ec- eca ecb ecc ecd ece ecf eco ecr ed- eda edb edc edd ede edf edo edr eea eeb eec eed eee eef eeo eer ef- efa efb efc efd efe eff efo efr eo- eoa eob eoc eod eoe eof eoo eor era erb erc erd ere erf ero err faa fab fac fad fae faf fao far fba fbb fbc fbd fbe fbf fbo fbr fca fcb fcc fcd fce fcf fco fcr fda fdb fdc fdd fde fdf fdo fdr fea feb fec fed fee fef feo fer ffa ffc ffd ffe fff ffo ffr foa fob foc foe fof foo for fra frb frc frd fre frf fro frr oaa oab oac oad oae oaf oao oar ob- oba obb obc obd obe obf obo obr oc- oca ocb occ ocd ocf oco ocr oda odb odc odd ode odf odo odr oea oeb oec oed oee oef oeo oer of- ofa ofb ofc ofd ofe off ofo ofr oo- ooa oob ooc ood oof ooo oor or- ora orb orc ord ore orf oro orr ra- raa rab rac rad rae raf rao rar rba rbb rbc rbd rbe rbf rbo rbr rca rcb rcc rcd rce rcf rco rcr rda rdb rdc rdd rde rdf rdo rdr re- rea reb rec red ree ref reo rer rfa rfb rfc rfd rfe rff rfo rfr roa rob roc rod roe rof roo ror rra rrb rrc rrd rrf rrr