Rocket Pack

Chef's robot starts from the coordinate $(0, 0)$ and wishes to reach to the coordinate $(N, M)$. The initial energy of the robot is $0$. There are $K$ `batteries` kept at some of the coordinates such that picking up the $i^{th}$ `battery` costs $C_i$ units, and, on picking the $i^{th}$ `battery`, the current energy of the robot becomes $E_i$. Note that one coordinate can have multiple `batteri