CF455A.Boredom

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.

The first line contains integer $n$ ( $1<=n<=10^{5}$ ) that shows how many numbers are in Alex's sequence.

The second line contains $n$ integers $a_{1}$ , $a_{2}$ , ..., $a_{n}$ ( $1<=a_{i}<=10^{5}$ ).

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

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.