#!/bin/python3

import sys

def largestValue(A):
    # Return the largest value of any of A's nonempty subarrays.
    G = {}  # (i, j): value
    S = {}  # sum[i, j]
    
    def getSum(i, j):
        p = i, j
        if p in S:
            return S[p]
        if i == j:
            S[p] = A[i]
            return S[p]
        S[p] = A[i] + getSum(i + 1, j)
        return S[p]
    
    def dfs(i, j):
        p = i, j
        if p in G:
            return G[p]
        if i == j:
            G[p] = 0
            return G[p]
        G[p] = A[i] * getSum(i + 1, j) + dfs(i + 1, j)
        return G[p]
    
    amax = float("-inf")
    for i in range(len(A)):
        for j in range(i, len(A)):
            amax = max(amax, dfs(i, j))
    return amax

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