You are walking with your dog, and now you are at the promenade. The promenade can be represented as an infinite line. Initially, you are in the point $$$0$$$ with your dog.

You decided to give some freedom to your dog, so you untied her and let her run for a while. Also, you watched what your dog is doing, so you have some writings about how she ran. During the $$$i$$$-th minute, the dog position changed from her previous position by the value $$$a_i$$$ (it means, that the dog ran for $$$a_i$$$ meters during the $$$i$$$-th minute). If $$$a_i$$$ is positive, the dog ran $$$a_i$$$ meters to the right, otherwise (if $$$a_i$$$ is negative) she ran $$$a_i$$$ meters to the left.

During some minutes, you were chatting with your friend, so you don't have writings about your dog movement during these minutes. These values $$$a_i$$$ equal zero.

You want your dog to return to you after the end of the walk, so the destination point of the dog after $$$n$$$ minutes should be $$$0$$$.

Now you are wondering: what is the maximum possible number of different integer points of the line your dog could visit on her way, if you replace every $$$0$$$ with some integer from $$$-k$$$ to $$$k$$$ (and your dog should return to $$$0$$$ after the walk)? The dog visits an integer point if she runs through that point or reaches in it at the end of any minute. Point $$$0$$$ is always visited by the dog, since she is initially there.

If the dog cannot return to the point $$$0$$$ after $$$n$$$ minutes regardless of the integers you place, print -1.

Input

The first line of the input contains two integers $$$n$$$ and $$$k$$$ ($$$1 \le n \le 3000; 1 \le k \le 10^9$$$) — the number of minutes and the maximum possible speed of your dog during the minutes without records.

The second line of the input contains $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ ($$$-10^9 \le a_i \le 10^9$$$), where $$$a_i$$$ is the number of meters your dog ran during the $$$i$$$-th minutes (to the left if $$$a_i$$$ is negative, to the right otherwise). If $$$a_i = 0$$$ then this value is unknown and can be replaced with any integer from the range $$$[-k; k]$$$.

Output

If the dog cannot return to the point $$$0$$$ after $$$n$$$ minutes regardless of the set of integers you place, print -1. Otherwise, print one integer — the maximum number of different integer points your dog could visit if you fill all the unknown values optimally and the dog will return to the point $$$0$$$ at the end of the walk.

Dog Walking

Examples