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;
const int N = 100010;
const int D = 20;
int n;
int a[N], s[N];
int f_min[N][D], f_max[N][D];
inline int smaller(int x, int y) { return s[x] < s[y] ? x : y; }
inline int larger(int x, int y) { return s[x] > s[y] ? x : y; }
int query_min(int x, int y) {
  int det = log2(y - x + 1);
  int res = smaller(f_min[x][det], f_min[y - (1 << det) + 1][det]);
  return res;
}
int query_max(int x, int y) {
  int det = log2(y - x + 1);
  int res = larger(f_max[x][det], f_max[y - (1 << det) + 1][det]);
  return res;
}
const int BASE = 30;
int prefix_pos[N][BASE * 2 + 10], suffix_pos[N][BASE * 2 + 10];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) {
    scanf("%d", a + i);
    s[i] = s[i - 1] + a[i];
    f_min[i][0] = f_max[i][0] = i;
    if (0) printf("%d%c", s[i], " \n"[i == n]);
  }
  for (int j = 1; (1 << j) <= (n + 1); ++j)
    for (int i = 0; i <= n; ++i) {
      f_max[i][j] = f_max[i][j - 1];
      f_min[i][j] = f_min[i][j - 1];
      int nex = i + (1 << (j - 1));
      if (nex > n) break;
      f_max[i][j] = larger(f_max[i][j], f_max[nex][j - 1]);
      f_min[i][j] = smaller(f_min[i][j], f_min[nex][j - 1]);
      if (0)
        printf("f_min[%d][%d]=%d, f_max[%d][%d]=%d\n", i, j, f_min[i][j], i, j,
               f_max[i][j]);
    }
  for (int i = 1; i <= n; ++i) {
    for (int j = 0; j <= BASE * 2; ++j) prefix_pos[i][j] = prefix_pos[i - 1][j];
    prefix_pos[i][a[i] + BASE] = i;
  }
  for (int j = 0; j <= BASE * 2; ++j) suffix_pos[n + 1][j] = n + 1;
  for (int i = n; i; --i) {
    for (int j = 0; j <= BASE * 2; ++j) suffix_pos[i][j] = suffix_pos[i + 1][j];
    suffix_pos[i][a[i] + BASE] = i;
  }
  int ans = 0;
  for (int i = 1; i <= n; ++i) {
    int L = 0, R = n + 1;
    for (int j = a[i] + 1 + BASE; j <= BASE * 2; ++j) {
      L = max(L, prefix_pos[i][j]);
      R = min(R, suffix_pos[i][j]);
    }
    int mi = query_min(L, i - 1);
    int ma = query_max(i, R - 1);
    if (0) printf("query_min: (%d, %d) -> [%d] %d\n", L, i - 1, mi, s[mi]);
    if (0) printf("query_max: (%d, %d) -> [%d] %d\n", i, R - i, ma, s[ma]);
    if (0)
      printf("max=[%d], seg=[%d, %d] res=(%d)-(%d)-(%d)\n", i, mi + 1, ma,
             s[ma], s[mi], a[i]);
    ans = max(ans, s[ma] - s[mi] - a[i]);
  }
  printf("%d\n", ans);
  return 0;
}
