You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 1-[1-(2,4-dichloro-5-fluorophenyl)ethyl]-3-[(6-propan-2-yloxypyridin-3-yl)methyl]urea into molecular formula.
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C18H20Cl2FN3O2
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