You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R)-2-(2-chloro-5-pyrazol-1-ylbenzoyl)-3,4-dihydro-1H-isoquinoline-3-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H17ClN4O2
assistant