You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-[1-[(3-fluorophenyl)methyl]-5-oxopyrrolidin-3-yl]-5-(methoxymethyl)thiophene-2-carboxamide into molecular formula.
user
C18H19FN2O3S
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