You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-pyrimidin-5-yl-9-(thiophene-2-carbonyl)-1-oxa-4,9-diazaspiro[5.5]undecan-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C17H18N4O3S
assistant