Alex doesn't like boredom. That's why whenever he gets bored, he comes up with games. One long winter evening he came up with a game and decided to play it. Given a sequence a consisting of n integers. The player can make several steps. In a single step he can choose an element of the sequence (let's denote it a k ) and delete it, at that all elements equal to a k + 1 and a k - 1 also must be deleted from the sequence. That step brings a k points to the player. Alex is a perfectionist, so he decided to get as many points as possible. Help him.

输入描述:

The first line contains integer n (1 ≤ n ≤ 105) that shows how many numbers are in Alex's sequence. The second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 105).

输出描述:

Print a single integer — the maximum number of points that Alex can earn.

备注:

Consider the third test example. At first step we need to choose any element equal to 2. After that step our sequence looks like this [2, 2, 2, 2]. Then we do 4 steps, on each step we choose any element equals to 2. In total we earn 10 points.