#!/bin/python3

import sys

def value(l):
    s = sum(l)
    res = 0
    for i in l:
        s = s - i
        res += s*i
    return res

def largestValue(n,A):
    res = 0
    for i in range(n):
        for j in range(i+1,n):
            temp = value(A[i:j+1])
            if(temp>res):
                res = temp
    return res

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