You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (5R)-5-(6-fluoro-1H-indol-3-yl)-4-methoxy-6-methyl-7,8-dihydro-5H-[1,3]dioxolo[4,5-g]isoquinoline into molecular formula.
user
C20H19FN2O3
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