You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 2-methyl-1-(4-morpholin-4-ylbutyl)-3-[[4-(2-oxopyrrolidin-1-yl)phenyl]methyl]guanidine by IUPAC nomenclature, provide its molecular formula.
user
C21H33N5O2
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