def maxSubArraySum(a): # Kadane
    size = len(a)
    maxsize = 10**6
    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 a[start:end+1]

def largestValue(a):
    pairs = []
    n = len(a)
    for i in range(n-1):
        for j in range(i+1, n):
            pairs.append(a[i]*a[j])
    return sum(pairs)

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