You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-(4-ethylphenyl)-3-oxopyrazolo[3,4-b]pyridin-1-yl]-N-(2-fluorophenyl)acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H19FN4O2
assistant