You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[6-(3-ethoxy-3-oxopropyl)-4-(4-fluorophenyl)-3-oxopyrazin-2-yl]piperazine-1-carboxylic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H23FN4O5
assistant