You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 7-N-(6-aminopyrimidin-4-yl)-5-N-(2-ethyl-6-fluoro-4-isocyanophenyl)-5-N,3-dimethylimidazo[4,5-b]pyridine-5,7-diamine into molecular formula.
user
C21H20FN9
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