#!/bin/python3

import sys
from itertools import combinations
def largestValue(A):
    # Return the largest value of any of A's nonempty subarrays.
    
    sub=[A[x:y+1] for x in range(0,len(A)) for y in range(x+1,len(A))]
    a=[]
    for i in sub:
        n=[]
        com=list(combinations(i,2))
        for j in com:
            n.append(j[0]*j[1])
        a.append(sum(n))
    return max(a)

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