The problem was in a long story format but let me simplify it for you :-)

Problem: Some genie has power P. He wants to grant n wishes of the form {xi, yi}. Now to grant i-th wish he needs to have at least power xi and after granting this wish his power becomes P-yi. In this process, his power shouldn't dip below zero. What are the maximum possible wishes he can grant?

Constraints: 1<=n<=100, 1<=P<=30000, 1<=x<=30000, -300<=y<=300

I couldn't solve this problem in test time, I've seen so many problems of this type but I always fail. I would be grateful if someone explains this. Thanks have a good day!