#!/bin/python3

import sys
import itertools

def largestValue(A):
    # Return the largest value of any of A's nonempty subarrays.
    new=[]
    final=[]
    n=len(A)
    for i in range(0, n):
        for j in range(i, n):
            sum = 0
            new=[]
            for k in range(i, j + 1):
                sum+=A[k]
                new.append(A[k])
            new.append(sum)
            final.append(new)
    
    final.sort(key=lambda x: x[-1])
    new = final[-1][:-1]
    
    pairs = itertools.combinations(new, 2)
    answer = 0
    for pair in pairs:
        answer += pair[0] * pair[1]
    return(answer)
                
                

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