You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-N-[[4-(diethylamino)-3-fluorophenyl]methyl]-1-N,1-N-dimethylpiperidine-1,4-dicarboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H31FN4O2
assistant