You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-[2-[4-(4-chlorophenyl)piperazin-1-yl]-2-oxoethyl]-1-(3-methylphenyl)guanidine;hydroiodide into molecular formula.
user
C20H25ClIN5O
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