a-a a-b aaa aab aad aan aas ab- aba abb abd abn abs ad- ada adb add adn ads an- ana anb and ann ans as- asa asb asd asn ass baa bab bad ban bas bba bbb bbd bbn bbs bda bdb bdd bds bna bnb bnd bnn bns bsa bsb bsd bsn bss daa dab dad dan das dba dbb dbd dbn dbs dda ddb ddd ddn dds dna dnb dnd dnn dns dsa dsb dsd dsn dss naa nab nad nan nas nba nbb nbd nbn nbs nda ndb ndd ndn nds nna nnb nnn nns nsa nsb nsd nsn nss saa sab sad san sas sba sbb sbd sbn sbs sda sdb sdd sdn sds sna snb snd snn sns ss- ssa ssb ssd ssn sss