You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (5S)-N-(3-methoxypropyl)-2-(morpholine-4-carbonyl)-4,5,6,7-tetrahydro-1-benzothiophene-5-carboxamide into its molecular formula.
user
C18H26N2O4S
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