You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-but-2-ynyl-1-methyl-8-piperazin-1-yl-2-[2-(pyrrolidine-1-carbonyl)phenoxy]purin-6-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H29N7O3
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