You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-2-ethyl-N-[5-(2-methylpropyl)-1,3-thiazol-2-yl]-3-oxopiperazine-1-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C14H22N4O2S
assistant