You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (4S)-5-[2-[[4-(2-methoxyphenyl)-1,2,4-triazol-3-yl]sulfanyl]acetyl]-4-methyl-3,4-dihydro-1H-1,5-benzodiazepin-2-one by IUPAC nomenclature, provide its molecular formula.
user
C21H21N5O3S
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