a-a a-b aaa aab aad aan aav ab- aba abb abd abn abv ad- ada adb add adn adv an- ana anb and ann anv av- ava avb avd avn baa bab bad ban bav bba bbb bbd bbn bda bdb bdd bdv bna bnb bnd bnn bnv bva bvb bvd bvn bvv daa dab dad dan dav dba dbb dbd dbn dbv dda ddb ddd ddn dna dnb dnd dnn dva dvb dvd dvn naa nab nad nan nav nba nbb nbd nbn nbv nda ndb ndd ndn ndv nna nnb nnn nnv nva nvb nvd nvn nvv v-a vaa vab vad van vav vba vbd vbv vdb vdd vdv vn- vna vnd vnv vva vvb vvv