You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(2R)-2-morpholin-4-yl-2-pyridin-3-ylethyl]-4H-thieno[3,2-b]pyrrole-5-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H20N4O2S
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