You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2R)-2-N-isoquinolin-6-ylsulfanyl-1-N-(2-thiophen-3-ylethyl)propane-1,2-diamine by IUPAC nomenclature, provide its molecular formula.
user
C18H21N3S2
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