#!/bin/python3

import sys
import itertools
def get_max(x):
    bestSoFar = 0
    bestNow = 0
    bestStartIndexSoFar = -1
    bestStopIndexSoFar = -1
    bestStartIndexNow = -1
    for i in range(len(x)):
        value = bestNow + x[i]
        if value > 0:
            if bestNow == 0:
                bestStartIndexNow = i
            bestNow = value
        else:
            bestNow = 0

        if bestNow > bestSoFar:
            bestSoFar = bestNow
            bestStopIndexSoFar = i
            bestStartIndexSoFar = bestStartIndexNow

    return bestSoFar, bestStartIndexSoFar, bestStopIndexSoFar
def largestValue(A):
    su=0
    r,a,b = get_max(A)
    A=A[a:b+1]
    re = [list(x) for x in itertools.combinations(A,2)]
    for i in re:
        su+=i[0]*i[1]
    return su
    # Return the largest value of any of A's nonempty subarrays.

if __name__ == "__main__":
    n = int(input().strip())
    A = list(map(int, input().strip().split(' ')))
    result = largestValue(A)
    print(result)