human
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.
# -*- ... What is a Python program to print a single integer — the final score of the game?
assistant
#Here is Python program to print a single integer — the final score of the game.
 coding: utf-8 -*-

import sys
# sys.setrecursionlimit(10**6)
# buff_readline = sys.stdin.buffer.readline
buff_readline = sys.stdin.readline
readline = sys.stdin.readline

INF = 2**62-1

def read_int():
    return int(buff_readline())

def read_int_n():
    return list(map(int, buff_readline().split()))

def read_float():
    return float(buff_readline())

def read_float_n():
    return list(map(float, buff_readline().split()))

def read_str():
    return readline().strip()

def read_str_n():
    return readline().strip().split()

def error_print(*args):
    print(*args, file=sys.stderr)

def mt(f):
    import time

    def wrap(*args, **kwargs):
        s = time.time()
        ret = f(*args, **kwargs)
        e = time.time()

        error_print(e - s, 'sec')
        return ret

    return wrap



def slv(N, A):
    from collections import Counter
    memo = {}
    memo[0] = 0
    ans = 0
    for a in A:
        nm = Counter()
        for k, v in memo.items():
            m = max(k, a)
            nm[m] = max(nm[m], v + a)
            ans = max(ans, nm[m]-m)
        nm[0] = 0
        memo = nm

    return ans


def main():
    N = read_int()
    A = read_int_n()
    print(slv(N, A))

if __name__ == '__main__':
    main()