You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(2-cyclopropyl-2-hydroxyethyl)-1-methyl-3-(2-methyl-1,2,3,4-tetrahydronaphthalen-1-yl)urea is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H26N2O2
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