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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastReader in = new FastReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        DYetAnotherYetAnotherTask solver = new DYetAnotherYetAnotherTask();
        solver.solve(1, in, out);
        out.close();
    }

    static class DYetAnotherYetAnotherTask {
        int[] a;
        int[] sum;
        int[] mx;

        public void solve(int testNumber, FastReader s, PrintWriter w) {
            int n = s.nextInt();
            a = new int[n + 1];
            sum = new int[n + 2];
            mx = new int[n + 2];
            for (int i = 1; i <= n; i++)
                a[i] = s.nextInt();
            w.println(calc(1, n, 30));
        }

        int calc(int l, int r, int val) {
            if (val == 0 || l > r) return 0;
            int mxLeft = 0;
            sum[l - 1] = 0;
            for (int i = l; i <= r; i++)
                sum[i] = sum[i - 1] + a[i];
            mx[r + 1] = sum[r];
            sum[r + 1] = sum[r];
            for (int i = r; i >= l; i--) mx[i] = Math.max(mx[i + 1], sum[i + 1]);
            int ans = 0;
            for (int i = l; i <= r; i++) {
                if (a[i] == val) {
                /*if(val == 10) {
                    if(a.length == 6) System.err.println(mxLeft+" "+(mx[i] - sum[i]));
                }*/
                    ans = Math.max(ans, mxLeft + Math.max(0, mx[i] - sum[i]));
                }
                mxLeft += a[i];
                if (mxLeft < 0) mxLeft = 0;
            }
            int ind = l;
            for (int i = l; i <= r; i++) {
                if (a[i] == val) {
                    ans = Math.max(ans, calc(ind, i - 1, val - 1));
                    ind = i + 1;
                }
            }
            ans = Math.max(ans, calc(ind, r, val - 1));
            //if(a.length == 6) System.err.println(l+" "+r+" "+ans+" "+val);
            return ans;
        }

    }

    static class FastReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private FastReader.SpaceCharFilter filter;

        public FastReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {

            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {

                curChar = 0;

                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }

            return buf[curChar++];
        }

        public int nextInt() {

            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();

                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public boolean isSpaceChar(int c) {

            if (filter != null)
                return filter.isSpaceChar(c);

            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}

