You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 4-[[4-[(2-fluorophenyl)methyl]-1,4-diazepan-1-yl]methyl]-1,5-dimethylpyrrole-2-carbonitrile into molecular formula.
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C20H25FN4
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