You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named (1S,2R,5E,7R,11S,13R,14S,18S)-9-amino-5-methoxyimino-2,18-dimethyl-10-thia-8-azapentacyclo[11.7.0.02,7.07,11.014,18]icos-8-en-17-one is given. What is its corresponding molecular formula?
user
C21H31N3O2S
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