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.
#include <bits/stdc++.h>
using namespace std;
template <typename T>
class SegmentTree {
  int left(int i) { return (2 * i + 1); }
  int right(int i) { return (2 * i + 2); }
  int pa(int i) { return (i - 1) / 2; }

 public:
  SegmentTree(const std::vector<T>& data,
              std::function<T(T, T)> f = std::plus<T>()) {
    this->f = f;
    this->n = data.size();
    levels = 1, el = 1;
    while (el < static_cast<int>(data.size())) {
      el <<= 1;
      ++levels;
    }
    tree.assign(2 * el, T());
    {
      for (size_t i = 0; i < data.size(); ++i) tree[i + el - 1] = data[i];
      for (int i = el - 2; i >= 0; --i)
        tree[i] = f(tree[2 * i + 1], tree[2 * i + 2]);
    }
  }
  SegmentTree(int n, T val = T(), std::function<T(T, T)> f = std::plus<T>())
      : SegmentTree(std::vector<T>(n, val), f) {}
  T get(int l, int r) { return query(l, r, 0, el, 0); }
  T get(int index) { return tree[el - 1 + index]; }
  void set(int index, T value) {
    int i = el - 1 + index;
    tree[i] = value;
    while (i > 0) {
      i = (i - 1) / 2;
      tree[i] = f(tree[i * 2 + 1], tree[i * 2 + 2]);
    }
  }

 private:
  std::vector<T> tree;
  int levels;
  int n;
  int el;
  std::function<T(T, T)> f;
  T query(int l, int r, int st, int fi, int node) {
    if (l <= st && r >= fi - 1) {
      return tree[node];
    }
    if (l == r) return get(l);
    int mid = (st + fi) / 2;
    if (r < mid) {
      return query(l, r, st, mid, left(node));
    } else if (l >= mid) {
      return query(l, r, mid, fi, right(node));
    } else {
      T lv = query(l, mid - 1, st, mid, left(node));
      T rv = query(mid, r, mid, fi, right(node));
      return f(lv, rv);
    }
  }
};
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  vector<long long> a(n);
  vector<long long> sum(n + 1, 0);
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    sum[i + 1] = sum[i] + a[i];
  }
  SegmentTree<long long> maxsum(
      sum, [](long long a, long long b) { return max(a, b); });
  SegmentTree<long long> minsum(
      sum, [](long long a, long long b) { return min(a, b); });
  SegmentTree<long long> aseg(
      a, [](long long a, long long b) { return max(a, b); });
  long long ans = 0;
  for (int i = 0; i < n; ++i) {
    int l = -1;
    int r = i;
    while (l + 1 < r) {
      int mid = (l + r) / 2;
      if (aseg.get(mid, i) <= a[i])
        r = mid;
      else
        l = mid;
    }
    int ll = l + 1;
    l = i;
    r = n;
    while (l + 1 < r) {
      int mid = (l + r) / 2;
      if (aseg.get(i, mid) <= a[i])
        l = mid;
      else
        r = mid;
    }
    int rr = l;
    ans = max(ans, maxsum.get(i + 1, rr + 1) - minsum.get(ll, i) - a[i]);
  }
  cout << ans;
}
