You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (2S)-3-methyl-2-[(1-methyl-4-oxo-5-phenylmethoxypyridine-2-carbonyl)amino]butanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H24N2O5
assistant