Alice and Bob are playing yet another card game. This time the rules are the following. There are n cards lying in a row in front of them. The i-th card has value a_i. 

First, Alice chooses a non-empty consecutive segment of cards [l; r] (l ≤ r). After that Bob removes a single card j from that segment (l ≤ j ≤ r). The score of the game is the total value of the remaining cards on the segment (a_l + a_{l + 1} + ... + a_{j - 1} + a_{j + 1} + ... + a_{r - 1} + a_r). In particular, if Alice chooses a segment with just one element, then the score after Bob removes the only card is 0.

Alice wants to make the score as big as possible. Bob takes such a card that the score is as small as possible.

What segment should Alice choose so that the score is maximum possible? Output the maximum score.

Input

The first line contains a single integer n (1 ≤ n ≤ 10^5) — the number of cards.

The second line contains n integers a_1, a_2, ..., a_n (-30 ≤ a_i ≤ 30) — the values on the cards.

Output

Print a single integer — the final score of the game.

Examples

Input


5
5 -2 10 -1 4


Output


6


Input


8
5 2 5 3 -30 -30 6 9


Output


10


Input


3
-10 6 -15


Output


0

Note

In the first example Alice chooses a segment [1;5] — the entire row of cards. Bob removes card 3 with the value 10 from the segment. Thus, the final score is 5 + (-2) + (-1) + 4 = 6.

In the second example Alice chooses a segment [1;4], so that Bob removes either card 1 or 3 with the value 5, making the answer 5 + 2 + 3 = 10.

In the third example Alice can choose any of the segments of length 1: [1;1], [2;2] or [3;3]. Bob removes the only card, so the score is 0. If Alice chooses some other segment then the answer will be less than 0.
import java.util.*;
import java.io.*;
import java.math.BigInteger;
import static java.lang.Math.*;
 
public class Main
{
	static final int mod = (int)1e9+7;
	public static void main(String[] args) throws Exception
	{
		FastReader in = new FastReader();
		PrintWriter out = new PrintWriter(System.out);
		int test = 1;
		while(test-- > 0)
		{
			int n = in.nextInt();
			long[] arr = new long[n];
			ArrayList<Integer>[] ind = new ArrayList[31];
			for(int i = 1; i <= 30; i++) {
				ind[i] = new ArrayList();
			}
			for(int i = 0; i < n; i++) {
				int a = in.nextInt();
				if(a > 0) {
					ind[a].add(i);
					arr[i] = Integer.MIN_VALUE;
				}
				else
					arr[i] = a;
			}
			long ans = 0;
			for(int i = 1; i <= 30; i++) {
				for(int j : ind[i]) {
					arr[j] = i;
				}
				long sum = 0, best = 0;
				for(int j = 0; j < n; j++) {
					if(sum + arr[j] > 0) {
						sum += arr[j];
						best = max(best, sum);
					}
					else {
						sum = 0;
					}
				}
				ans = max(ans, best - i);
			}
			out.println(ans);
		}
		out.flush();
	}

	static double check(double h, double c, double t, double m) {
		double val = (m - 1) * (h + c) + h + h;
		val /= m + m;
		return abs(t - val);
	}
}

class FastReader
{
	BufferedReader br;
	StringTokenizer st;
 
	public FastReader()
	{
	    br = new BufferedReader(new InputStreamReader(System.in));
	}
 
	public String next() throws IOException
	{
	    if(st == null || !st.hasMoreElements())
	    {
	        st = new StringTokenizer(br.readLine());
	    }

	    return st.nextToken();
	}

	public boolean hasNext() throws IOException
	{
		if(st != null && st.hasMoreElements())
		{
			return true;
		}

		String s = br.readLine();
		if(s == null) {
			return false;
		}

		st = new StringTokenizer(s);

		return st.hasMoreElements();
	}
 
	public int nextInt() throws IOException
	{
	    return Integer.parseInt(next());
	}
 
	public long nextLong() throws IOException
	{
	    return Long.parseLong(next());
	}
 
	public String nextLine() throws IOException
	{
		return br.readLine();
	}
}