Discounts-2

In an electronics supermarket, a discount system is in place: if you buy one item, you pay the full price. If you purchase two items, you get a 50% discount on the cheaper item. For three items, the cheapest one is free. Determine the minimum amount you need to pay when buying N items, given that the prices of these items in hryvnias are listed in the array C[1..N].

Input data: The first line contains the integer N (1 ≤ N ≤ 100). The second line contains N integers representing the array C[1..N], where each value is a natural number not exceeding 10000.

Output data: Output the total cost of the purchase in standard monetary format.

Examples