"B & D' means 'B is the mother of D',
"B x D' means 'B is the husband of D'.
"B # D' means 'B is the sister of D'.
"B $ D' means 'B is the son of D'.
B @ D' means 'B is the father of D',
then how is P related to U in the following expression? P $ Q × R # S % T $ U