You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-ethyl-N-[4-[(E)-(9-methyl-5-oxo-2,3-dihydro-1-benzoxepin-4-ylidene)methyl]-1,3-thiazol-2-yl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H20N2O3S
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