You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[2-ethoxy-4-methoxy-3-[(1-oxothian-1-ylidene)amino]benzoyl]-2-ethyl-1H-pyrazol-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H27N3O5S
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