You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(6,7-dihydroxy-9H-pyrimido[4,5-b]indol-4-yl)-N-(4-methylsulfonylphenyl)piperazine-1-carbothioamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H22N6O4S2
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