You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[ethyl-[2-[3-[(9H-fluoren-9-ylmethoxycarbonylamino)methyl]cyclobutyl]acetyl]amino]propanoic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C27H32N2O5
assistant