You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-methyl-2-[[5-(2-phenylpropyl)-1,3,4-oxadiazol-2-yl]sulfanylmethyl]quinazolin-4-one into its molecular formula.
user
C21H20N4O2S
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