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.io.*;
import java.util.*;

public class G644 {

    public static void solve(InputReader in, PrintWriter out) throws Exception {


        int n  = in.nextInt();

        int[] arr = new int[n];

        for(int i=0;i<n;i++)
            arr[i]=in.nextInt();

        int ans =0;

        for(int i=1;i<=30;i++)
        {
            int curr =0;

            for(int j=0;j<n;j++)
            {
                if(arr[j]<=i)
                {
                    curr=curr+arr[j];
                }
                else
                    curr=0;

                curr=Math.max(curr,0);

                ans = Math.max(ans,curr-i);
            }
        }

        out.println(ans);


        }

    /////////////////////////////////////////////////////////


    private final static long hash(long x, long y) {
        x += offset;
        y += offset;
        return x << 32 | y;
    }

    private final static int offset = (int) 3e5;

    public static void main(String[] args) throws Exception {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        solve(in, out);
        out.close();
    }

    static class InputReader {
        private BufferedReader reader;
        private StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        private String nextToken() throws IOException {
            while (tokenizer == null || !tokenizer.hasMoreTokens())
                tokenizer = new StringTokenizer(reader.readLine());
            return tokenizer.nextToken();
        }

        public String nextLine() throws IOException {
            return reader.readLine();
        }

        public int nextInt() throws IOException {
            return Integer.parseInt(nextToken());
        }

        public long nextLong() throws IOException {
            return Long.parseLong(nextToken());
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(nextToken());
        }

    }
}