You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(Z)-4-(4-hydroxyanilino)-3-[[2-methyl-5-(3-methylphenyl)-1,2,4-triazol-3-yl]amino]but-2-enal The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H21N5O2
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