You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[5-(3,4-dichlorophenyl)pentan-2-yl]-1-ethyl-4-hydroxy-5-oxo-2H-pyrrole-3-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22Cl2N2O3
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