You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 3-[(Z)-[(1S,5R)-6,6-dimethyl-2-bicyclo[3.1.1]hept-2-enyl]methylideneamino]-8-methyl-5H-pyrimido[5,4-b]indol-4-one by IUPAC nomenclature, provide its molecular formula.
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C21H22N4O
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