You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (2S)-1-[3-[(4-fluorophenyl)methyl]-1,2,4-thiadiazol-5-yl]-N-[(2R)-3-methylbutan-2-yl]pyrrolidine-2-carboxamide into molecular formula.
user
C19H25FN4OS
assistant