from sys import maxsize
def maxSubArraySum(a,size):
 
    max_so_far = -maxsize - 1
    max_ending_here = 0
    start = 0
    end = 0
    s = 0
 
    for i in range(0,size):
 
        max_ending_here += a[i]
 
        if max_so_far < max_ending_here:
            max_so_far = max_ending_here
            start = s
            end = i
 
        if max_ending_here < 0:
            max_ending_here = 0
            s = i+1
 
    return [start,end]
n=int(input())
a=[int(x) for x in input().split()]
x=maxSubArraySum(a,n)
#print(x)
l=x[0]
r=x[1]
m=[]
sum=0
for i in range(l,r):
    for j in range(i+1,r+1):
        m.append(a[i]*a[j])
#print(m)
for i in range(len(m)):
    sum+=m[i]
print(sum)