a-a a-b a-z aaa aab aad aaf aar aaz ab- aba abb abd abf abr abz ad- ada adb add adf adr adz af- afa afb afd aff afr afz ar- ara arb ard arf arr arz az- aza azb azd azf azz baa bab bad baf bar baz bba bbb bbd bbf bbr bda bdb bdd bdf bdr bdz bfa bfb bfd bff bfr bfz bra brb brd brf brr brz bza bzd bzf bzr bzz daa dab dad daf dar daz dba dbb dbd dbf dbr dbz dda ddb ddd ddf ddr ddz dfa dfb dfd dff dfr dfz dra drb drd drr drz dza dzb dzd dzr faa fab fad faf far faz fba fbb fbd fbf fbr fda fdb fdd fdf fdr ffa ffd fff ffr ffz fra frb frd frf frr fzd ra- raa rab rad raf rar raz rba rbb rbd rbf rbr rda rdb rdd rdf rdr rfa rfb rfd rff rfr rfz rra rrb rrd rrf rrr rza rzb zaa zab zad zaf zar zaz zbb zbr zdf zfa zfd zfr zzr zzz