You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 5-ethyl-4-methyl-N-(2-oxo-3,4-dihydro-1H-quinolin-6-yl)thiophene-2-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C17H18N2O2S
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