You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (7S)-2-(4-methoxyphenyl)-N-(3-methylsulfanylphenyl)-5-oxo-6,7-dihydro-4H-pyrazolo[1,5-a]pyrimidine-7-carboxamide into its molecular formula.
user
C21H20N4O3S
assistant