Bulk Discount

A shop has $N$ items for sale. The $i$-th item has a cost of $A_i$. You would like to purchase all $N$ items. The shop offers a discount: whenever an item is bought, all future purchases have their costs reduced by $1$. However, the cost of an item also cannot fall below $0$. You can buy the items **in any order** you like. What's the minimum possible cost of purchasing all $N$ items? ### Inp