You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (2S)-2-[[4-(4-chlorophenyl)-1,4,6,7-tetrahydroimidazo[4,5-c]pyridine-5-carbonyl]amino]-3-methylbutanoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H23ClN4O3
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