You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(4-ethylphenyl)-5-[(5-methyl-2-phenyl-1,3-oxazol-4-yl)methyl]-1,2,3,3a-tetrahydropyrazolo[1,5-a]pyrazin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C25H26N4O2
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