You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[2-(3,4-dihydro-2H-quinolin-1-yl)-2-oxoethyl]-5-fluoroindole-3-carbaldehyde by IUPAC nomenclature, provide its molecular formula.
user
C20H17FN2O2
assistant