a-a aaa aad aaf aag aan ad- ada add adf adg adn af- afa afd aff afg afn ag- aga agd agf agg agn an- ana and anf ang ann daa dad daf dag dan dda ddd ddf ddg ddn dfa dfd dff dfg dfn dga dgd dgf dgg dgn dna dnd dnf dng dnn faa fad faf fag fan fda fdd fdf fdg fdn ffa ffd fff ffg ffn fga fgd fgf fgg fgn fna fnd fnf fng fnn g-d gaa gad gaf gag gan gda gdd gdf gdn gfa gfd gff gga ggd ggg ggn gna gnd gnf gnn naa nad naf nag nan nda ndd ndf ndg ndn nfa nfd nff nfn nga ngd ngf ngg ngn nna nnf nng nnn