You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(7-methoxy-3-phenyl-3,4-dihydro-1H-isoquinolin-2-yl)-(2-methylpyrazol-3-yl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H21N3O2
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