You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name [(3S)-4-ethyl-3-(1H-imidazol-2-yl)piperazin-1-yl]-(2-methoxypyridin-3-yl)methanone into its molecular formula.
user
C16H21N5O2
assistant