You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (1S,2S,6R,7S)-7-(4-chlorophenyl)-1-(4-nitrophenyl)-8,10-dioxatricyclo[5.2.1.02,6]dec-3-en-9-one by IUPAC nomenclature, provide its molecular formula.
user
C20H14ClNO5
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