You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(7-chloro-3-cyclohexyl-4-oxoquinazolin-2-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
C20H21ClN4O3S
assistant