a-a a-b a-i aaa aab aaf aag aai aan ab- aba abb abf abg abi abn af- afa afb aff afg afi afn ag- aga agb agf agg agi agn ai- aia aib aif aig aii ain an- ana anb anf ang ani ann baa bab baf bag bai ban bba bbb bbf bbg bbi bbn bfa bfb bff bfg bfi bfn bga bgb bgf bgg bgi bgn bi- bia bib bif big bii bin bna bnb bnf bng bni bnn faa fab faf fag fai fan fba fbb fbf fbg fbi fbn ffa fff ffg ffi ffn fga fgb fgf fgg fgi fgn fia fib fif fig fii fin fna fnb fnf fng fni fnn gaa gab gaf gag gai gan gba gbf gbg gbi gbn gfa gfb gff gfi gga ggb ggg ggi ggn gia gib gif gig gii gin gna gnb gnf gni gnn i-f ia- iaa iab iaf iag iai ian iba ibb ibf ibg ibi ibn ifa ifb iff ifg ifi ifn iga igb igf igg igi ign iia iib iif iii iin in- ina inb inf ing ini inn n-i naa nab naf nag nai nan nba nbb nbf nbg nbi nbn nfa nfb nff nfi nfn nga ngb ngf ngg ngi ngn nia nib nif nig nii nin nna nnb nnf nng nni nnn