You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(2-chlorophenoxy)-N-[2-(1,1-dioxothiolan-3-yl)-5-phenylpyrazol-3-yl]acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H20ClN3O4S
assistant