You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named [4-[(3-fluorophenyl)methyl]piperazin-1-yl]-[3-(4-fluorophenyl)-1H-pyrazol-5-yl]methanone is given. What is its corresponding molecular formula?
user
C21H20F2N4O
assistant