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.
import sys,os,io
input = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline

PI = 3.141592653589793238460
INF =  float('inf')
MOD  = 1000000007
# MOD = 998244353


def bin32(num):
    return '{0:032b}'.format(num)

def add(x,y):
    return (x+y)%MOD

def sub(x,y):
    return (x-y+MOD)%MOD

def mul(x,y):
    return (x*y)%MOD

def gcd(x,y):
    if y == 0:
        return x
    return gcd(y,x%y)

def lcm(x,y):
    return (x*y)//gcd(x,y)

def power(x,y):
    res = 1
    x%=MOD
    while y!=0:
        if y&1 :
            res = mul(res,x)
        y>>=1
        x = mul(x,x)
        
    return res
        
def mod_inv(n):
    return power(n,MOD-2)

def prob(p,q):
    return mul(p,power(q,MOD-2))    
  
def ii():
    return int(input())

def li():
    return [int(i) for i in input().split()]

def ls():
    return [i for i in input().split()]




n = ii()
a = li()
dp = [ [ -INF for i in range( 62)] for j in range(n) ]

dp[0][a[0] + 30] = 0
ans = 0
for i in range(1 , n):
    x = a[i] + 30
    for j in range(x +1):
        dp[i][x] = max( dp[i][x] , dp[i-1][j] + j - 30 , 0 )
        ans = max(ans , dp[i][j])
    for j in range(x+1 , 62):
        dp[i][j] = max ( dp[i][j] , dp[i-1][j  ] +a[i] )  
        ans = max(ans , dp[i][j])

print(ans)
        




