#!/usr/bin/env python3

def trade_strength(profits):
    n = len(profits)

    #OPT(j) =
    #max[1<=i<=j](Profit from day i to j inclusive) IF j  is in the max subsequence
    #OPT(j-1)                                       IF j not in the max subsequence

    #sumP[idx] = Sum of profits from day 1 to day idx (inclusive)
    #Sum of profits from day a to day b (inclusive) = sumP[b] - sumP[a-1]
    sumP = [0]

    running_sum = 0
    for profit in profits:
        running_sum += profit
        sumP.append(running_sum)

    #M[idx] = Optimum at day idx
    M = [None,profits[0]]

    #From day 2 to last (inclusive)
    for day_end in range(2,n+1):
        #Start max at previous optimum
        max_for_day_end = M[day_end-1]
        #From day 1 to day_end (inclusive)
        for day_start in range(1,day_end+1):
            profit_sum = sumP[day_end] - sumP[day_start-1]
            if profit_sum > max_for_day_end:
                max_for_day_end = profit_sum
        M.append(max_for_day_end)

    return M[-1]


#P[idx] = Pay at day (idx+1)
P = [-1,3,3,3,-1,-1,-1,2]

print(trade_strength(P))