You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[3-[(5R)-3-(4-methylphenyl)-6-oxo-4,5-dihydro-1H-pyridazin-5-yl]indol-1-yl]propanenitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H20N4O
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