You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-2-amino-6-[3-[(5S)-5-amino-5-carboxypentyl]imidazol-1-ium-1-yl]hexanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C15H26N4O4
assistant