You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 2-[(7-methyl-4-oxo-8-phenyl-3H-pyrazolo[1,5-a][1,3,5]triazin-2-yl)sulfanyl]-N-(oxolan-2-ylmethyl)acetamide into its molecular formula.
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C19H21N5O3S
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