You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-[[5-[5-(2-chloroethyl)-2,4-dioxopyrimidin-1-yl]-3-hydroxyoxolan-2-yl]methoxy]-2-oxoethyl]phosphonic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H18ClN2O9P
assistant