You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(2,6-dimethyl-2,3-dihydro-1H-inden-1-yl)-3-[(4-hydroxyoxan-4-yl)methyl]urea is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H26N2O3
assistant