You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 5-O-methyl 2-O-(2-methylsulfanylethyl) (5S,6S)-3,6-dimethyl-4-oxo-1,5,6,7-tetrahydroindole-2,5-dicarboxylate into its molecular formula.
user
C16H21NO5S
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