You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 1-[2-[6-(5-propylthiophene-3-carbonyl)-7,8-dihydro-5H-pyrido[4,3-d]pyrimidin-2-yl]pyrrolidin-1-yl]ethanone into molecular formula.
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C21H26N4O2S
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