You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(6Z)-6-[[2,5-dimethyl-1-[3-(trifluoromethyl)phenyl]pyrrol-3-yl]methylidene]-2-ethyl-5-imino-[1,3,4]thiadiazolo[3,2-a]pyrimidin-7-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H18F3N5OS
assistant