You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-[(3-tert-butyl-1,2,4-oxadiazol-5-yl)methyl]-3-oxopiperazin-2-yl]acetic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C13H20N4O4
assistant