#!/bin/python

import sys

def largestValue(A):
    dp = [0]
    for i in range(1, n):
        s = 0
        v = 0
        ans = -10**6
        for j in range(i-1, -1, -1):
            s = s + A[j]
            v = v + 2*A[j]*(s-A[j])
            if v+2*s*A[i]>ans:
                ans = v + 2*s*A[i]
        dp.append(ans)
    returnval =  max(dp)
    return returnval/2

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