Susobhan in BorrowLand

Mr Susobhan lives in the city of Borrow-Land. He is looking to borrow as much money he can before he catches a flight to London. The city of Borrow-Land can be considered as an infinite grid. There are n lenders in the city located at a point (xi , yi ) who can lend at most Wi money. But Mr Susobhan borrows all the money the lender has. No two lenders share the same location and no lender is pres