You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(2S)-4-(1-methylpyrrol-2-yl)butan-2-yl]-3-(6-pyrazol-1-ylpyridin-3-yl)urea The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H22N6O
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