a-a a-b a-i aaa aab aae aaf aai aan ab- aba abb abe abf abi abn aea aeb aee aef aei aen af- afa afb afe aff afi afn ai- aia aib aie aif aii ain an- ana anb ane anf ani ann baa bab bae baf bai ban bba bbb bbe bbf bbi bbn be- bea beb bee bef bei ben bfa bfb bfe bff bfi bfn bi- bia bib bie bif bii bin bna bnb bne bnf bni bnn eaa eab eae eaf eai ean eba ebb ebe ebf ebi ebn eea eeb eee eef een ef- efa efb efe eff efi eia eib eie eif eii ein en- ena enb ene enf eni enn faa fab fae faf fai fan fba fbb fbe fbf fbi fbn fea feb fee fef fei fen ffa ffe fff ffi ffn fia fib fie fif fii fin fna fnb fne fnf fni fnn i-f ia- iaa iab iae iaf iai ian iba ibb ibe ibf ibi ibn ie- iea iee ief iei ien ifa ifb ife iff ifi ifn iia iib iie iif iii iin in- ina inb ine inf ini inn n-i naa nab nae naf nai nan nba nbb nbe nbf nbi nbn ne- nea neb nee nef nei nen nfa nfb nfe nff nfi nfn nia nib nie nif nii nin nna nnb nne nnf nni nnn