You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-[(2-chlorophenyl)methyl]indol-3-yl]sulfanyl-N-(5-methyl-1,2-oxazol-3-yl)acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H18ClN3O2S
assistant