You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 2-[(4-bromo-2-methylphenyl)methyl]-1-ethyl-3-[(2-oxo-3,4-dihydro-1H-quinolin-4-yl)methyl]guanidine into its molecular formula.
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C21H25BrN4O
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