You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-(3-chloro-4-cyanoanilino)-2-oxoethyl] 4H-thieno[3,2-c]chromene-2-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H13ClN2O4S
assistant