You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (6,7-dimethoxy-4-oxo-3H-quinazolin-2-yl)methyl-ethyl-[2-oxo-2-[[(2R)-pentan-2-yl]amino]ethyl]azanium into molecular formula.
user
C20H31N4O4+
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