You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (E)-1-(4-methylpiperazin-1-yl)-3-(1-phenyl-3-thiophen-2-ylpyrazol-4-yl)prop-2-en-1-one by IUPAC nomenclature, provide its molecular formula.
user
C21H22N4OS
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