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.
impor
assistant
#Here is Python program to print a single integer — the final score of the game.
t collections
FAST_IO = 0
if FAST_IO:
    import io, sys, atexit
    rr = iter(sys.stdin.read().splitlines()).next
    sys.stdout = _OUTPUT_BUFFER = io.BytesIO()
    @atexit.register
    def write():
        sys.__stdout__.write(_OUTPUT_BUFFER.getvalue())
else:
    rr = raw_input
rri = lambda: int(rr())
rrm = lambda: map(int, rr().split())
 
 
 
def solve(N, A):
    NINF = float('-inf')
    #dp[m] = max subarray sum ending at A[i] with max m
    dp = [NINF] * 61
    ans = 0
    for x in A:
        ndp = [NINF] * 61
        ndp[x] = max(x, 0)
        bns = NINF
        for m1 in xrange(0, x):
            bns = max(bns, dp[m1])
        for m1 in xrange(x, 31):
            bns = max(bns, dp[m1])
            ndp[m1] = max(ndp[m1], bns + x)
        dp = ndp
        for i in xrange(-30, 31):
            ans = max(ans, dp[i] - max(0, i))
        #print("!", x, ans)
    return ans
    
    
n = rri()
arr = rrm()
print(solve(n, arr))