You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name [2-[bis(phosphonomethyl)amino]ethyl-[2-[2-[bis(phosphonomethyl)amino]ethyl-(phosphonomethyl)amino]ethyl]amino]methylphosphonic acid into its molecular formula.
user
C12H36N4O18P6
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