-er a-a a-b aaa aab aad aae aar aav ab- aba abb abd abe abr abv ad- ada adb add ade adr adv aea aeb aed aee aer aev ar- ara arb ard are arr arv av- ava avb avd ave avr baa bab bad bae bar bav bba bbb bbd bbe bbr bda bdb bdd bde bdr bdv be- bea beb bed bee ber bev bra brb brd bre brr brv bva bvb bvd bve bvr bvv daa dab dad dae dar dav dba dbb dbd dbe dbr dbv dda ddb ddd dde ddr de- dea deb ded dee der dev dra drb drd dre drr drv dva dvb dvd dve dvr eaa eab ead eae ear eav eba ebb ebd ebe ebr ebv ed- eda edb edd ede edr eea eeb eed eee eer eev era erb erd ere err erv eva evb evd eve evr evv ra- raa rab rad rae rar rav rba rbb rbd rbe rbr rda rdb rdd rde rdr rdv re- rea reb red ree rer rev rra rrb rrd rrr rva rvb rvd rve rvr rvv v-a v-e vaa vab vad vae var vav vba vbd vbr vbv vdb vdd vde vdr vdv vea veb ved vee ver vra vrb vrd vre vrr vva vvb vvr vvv