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>
#pragma GCC optimize("Ofast")
using namespace std;
using i64 = int;
using i32 = int;
using f64 = long double;
template <class Key>
using vec = vector<Key>;
template <class Key>
using hash_set = unordered_set<Key>;
template <class Key, class Value>
using hash_map = unordered_map<Key, Value>;
using str = string;
template <size_t Size1>
using a64 = array<i64, Size1>;
template <size_t Size1, size_t Size2>
using aa64 = array<a64<Size2>, Size1>;
using p64 = pair<i64, i64>;
using v64 = vec<i64>;
using vv64 = vec<v64>;
using s64 = set<i64>;
using m64 = map<i64, i64>;
mt19937 gen(998244353);
const i64 inf = numeric_limits<i64>::max() / 2;
template <class T>
inline i64 sz(const T& a) {
  return (i64)(a.size());
}
inline void fast() { ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0); }
template <class T, class S>
inline bool check_min(T& a, S b) {
  if (a > b) return a = b, 1;
  return 0;
}
template <class T, class S>
inline bool check_max(T& a, S b) {
  if (a < b) return a = b, 1;
  return 0;
}
void read() {}
void print() {}
template <class T, class... U>
void read(T& a, U&... b) {
  cin >> a;
  read(b...);
}
template <class T, class... U>
void print(const T& a, const U&... b) {
  cout << a;
  print(b...);
}
struct Problem {
  void files(str in, str out) {
    freopen(in.c_str(), "r", stdin), freopen(out.c_str(), "w", stdout);
  }
  void solve(), input();
  void many() {
    i64 t;
    cin >> t;
    while (t--) input(), solve();
  }
  void make(bool mt = 0) {
    if (mt)
      many();
    else
      input(), solve();
  }
} problem;
signed main() {
  fast();
  problem.make();
  return 0;
}
i64 n;
v64 a;
const i64 MAXC = 30;
void Problem::solve() {
  vec<hash_map<i64, i64>> dp(n + 1);
  for (i64 k = -MAXC; k <= MAXC; k++) {
    dp[0][k] = 0;
  }
  i64 ans = 0;
  for (i64 i = 1; i <= n; i++) {
    for (i64 k = -MAXC; k <= MAXC; k++) {
      dp[i][k] = -inf;
    }
    dp[i][a[i]] = a[i];
    for (i64 k = -MAXC; k <= MAXC; k++) {
      if (a[i] >= k) {
        check_max(dp[i][a[i]], dp[i - 1][k] + a[i]);
      } else {
        check_max(dp[i][k], dp[i - 1][k] + a[i]);
      }
    }
    for (i64 k = -MAXC; k <= MAXC; k++) {
      if (check_max(ans, dp[i][k] - k)) {
        continue;
      }
    }
  }
  cout << ans << "\n";
}
void Problem::input() {
  read(n);
  a.assign(n + 1, 0);
  for (i64 i = 1; i <= n; i++) {
    read(a[i]);
  }
}
