You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
tert-butyl 2-[4-chloro-6-(4-chloro-3-fluorophenyl)pyridin-2-yl]oxy-2-methylpropanoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H20Cl2FNO3
assistant