Chef Diet

Chef decided to go on a diet during the following $N$ days (numbered 1 through $N$). Part of the diet plan is to eat $K$ grams of protein during each day. For each valid $i$, Chef wants to buy $Ai$ grams of protein in the morning of the $i$-th day and then eat $K$ grams of protein as part of his dinner. If he has any protein remaining, he can store it and use it in later dinners. Initially, Chef i