You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-(3-methyl-2,6-dioxo-7H-purin-8-yl)-N-[2-[2-(trifluoromethyl)phenyl]ethyl]propanamide into molecular formula.
user
C18H18F3N5O3
assistant