n = int(input())
a = list(map(int, input().split()))
max_ending = 0
max_so_far = -99999999999999
start = 0
end = 0
s = 0 
for i in range(0, n):
	max_ending += a[i]
	if max_so_far < max_ending:
		max_so_far = max_ending
		start = s
		end = i
	if max_ending < 0:
		max_ending = 0
		s = i+ 1
s = start
e = end
dp = [[0 for i in range(n)] for i in range(n)]
sm=0
for i in range(s,e+1):
    for j in range(i+1,e+1):
        dp[i][j] = a[i] * a[j]
        sm += dp[i][j]
print(sm)