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.
N = int(input())
A = [int(_) for _ in input().split()]

dp = [[0] * 63 for _ in range(N+1)]
dp[0][A[0]+30] = A[0]

answer = 0

for i in range(1, N):
    el = A[i]
    iel = el+30
    dp[i][iel] = max(dp[i][iel], el)
    answer = max(answer, dp[i][iel] - max(el, 0))
    for m in range(-30, 31):
        im = m + 30
        if el > m:
            dp[i][iel] = max(dp[i][iel], dp[i-1][im] + el)
            answer = max(answer, dp[i][iel] - max(el, 0))
        else:
            if dp[i-1][im] > 0:
                dp[i][im] = max(dp[i][im], dp[i-1][im] + el)
                answer = max(answer, dp[i][im] - max(m, 0))
        # dp[i][max(iel, im)] = max(el, dp[i][max(iel, im)], dp[i-1][m] + el)
        # if dp[i][max(iel, im)] - max(m, el) > answer:
        #     print('new answer', answer, 'at', i, max(m, el))
        #     answer = max(answer, dp[i][max(iel, im)] - max(m, el))

print(answer)
