You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-(4-ethylphenyl)-3-[[(2R)-4-(2-methylpropyl)morpholin-4-ium-2-yl]methyl]thiourea by IUPAC nomenclature, provide its molecular formula.
user
C18H30N3OS+
assistant