You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
11-acetyl-4-(3-chlorophenyl)-6-prop-2-ynyl-8-thia-4,6,11-triazatricyclo[7.4.0.02,7]trideca-1(9),2(7)-diene-3,5-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H16ClN3O3S
assistant