You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule [2-[[(2S)-2-cyano-3-methylbutan-2-yl]amino]-2-oxoethyl] 4-(2,3-dihydro-1H-inden-5-yl)-4-oxobutanoate into molecular formula.
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C21H26N2O4
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