You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(S)-(4-fluorophenyl)-(1-methylimidazol-2-yl)methyl]-1,4,6-trimethyl-2-oxopyridine-3-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
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C20H21FN4O2
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