E - Greedy Prices

There are $N$ items for sale at an auction. However, the auction is greedy and has made the prices variable depending on how much it perceives you will be able to pay. If you have already spent some amount of money, then it will increase the cost proportionally, as you are more likely to be willing to buy the item even at a higher price. Formally, the $i$-th item has 2 parameters $M_i$ and $C_i$,