You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5S)-7-propylsulfonyl-N-(pyridin-3-ylmethyl)-6,8-dihydro-5H-imidazo[1,5-a]pyrazine-5-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C16H21N5O3S
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