You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (E,4S)-4-[[2-[(2-amino-3-methoxy-2-methylpropanoyl)amino]acetyl]-methylamino]-2,5-dimethylhex-2-enoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H33N3O5
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