You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 1-[4-(4-amino-6-isocyanopyrrolo[2,1-f][1,2,4]triazin-5-yl)phenyl]-3-(2-methylpyridin-4-yl)urea .
user
C20H16N8O
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