You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance methyl 4-[[1-(3-methylphenyl)-4-oxo-5H-pyrazolo[3,4-d]pyrimidin-6-yl]sulfanylmethyl]benzoate .
user
C21H18N4O3S
assistant