a-a a-c aaa aac aae aaf aan ac- aca acc ace acf acn aea aec aee aef aen af- afa afc afe aff afn an- ana anc ane anf ann c-- caa cac cae caf can cca ccc cce ccf ccn ce- cea cec cee cef cen cfa cfc cfe cff cfn cn- cna cnc cne cnf cnn eaa eac eae eaf ean ec- eca ecc ece ecf ecn eea eec eee eef een ef- efa efc efe eff en- ena enc ene enf enn faa fac fae faf fan fca fcc fce fcf fcn fea fec fee fef fen ffa ffc ffe fff ffn fna fnc fne fnf fnn naa nac nae naf nan nca ncc nce ncf ncn ne- nea nec nee nef nen nfa nfc nfe nff nfn nna nnc nne nnf nnn