You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by 2-[[(2Z)-2-[7,8-bis(difluoromethoxy)-1-oxoisochromen-4-ylidene]acetyl]amino]pyridine-3-carboxylic acid ?
user
C19H12F4N2O7
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