You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R)-1-(4-chlorobenzoyl)-3-[(4-cyclopropyl-5-oxo-1H-1,2,4-triazol-3-yl)sulfanyl]azepan-2-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H19ClN4O3S
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