You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(5-bromo-2-methyl-1H-indol-3-yl)-N-[2-(4-pyrazol-1-ylphenyl)ethyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H21BrN4O
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