n = input("")
arr = input("").split(" ")
for i in range(len(arr)) :
    arr[i] = int(arr[i])

maxval = 0
maxlen = 0
maxstart = 0

for i in range(2,len(arr)) :
    for j in range(0,len(arr)-i+1) :
        sum = 0
        for k in range(j,i+j) :
            sum += arr[k]
        else:
            if sum > maxval :
                maxval = sum
                maxlen = i
                maxstart = j

prod = []

for i in range(maxstart,maxstart+maxlen-1) :
    for j in range(i+1,maxstart+maxlen) :
        prod.append(arr[i]*arr[j])
sum = 0
for i in prod :
    sum += i
print(sum)
#print(maxlen,maxstart)
#print(prod)