def mcs(a, low, mid, high):
        left_s = -(10 ** 7)
        s = 0
        max_left, max_right = -1, -1
        for i in range(mid, low - 1, -1):
            s = s + a[i]
            if (s > left_s):
                left_s = s
                max_left = i
        s = 0
        right_s = -(10 ** 7)

        for j in range(mid + 1, high + 1):
            s = s + a[j]
            if (s > right_s):
                right_s = s
                max_right = j

        return (max_left, max_right, left_s + right_s)


def ms(a, low, high):

        if (high == low):
            return (low, high, a[low])
        else:
            mid = (low + high) // 2

            left_low, left_high, left_sum =ms(a,low,mid)
            right_low, right_high, right_sum = ms(a, mid + 1, high)
            cross_low, cross_high, cross_sum = mcs(a, low, mid, high)
            if (left_sum >= right_sum and left_sum >= cross_sum):
                return (left_low, left_high, left_sum)
            elif (right_sum >= left_sum and right_sum >= cross_sum):
                return (right_low, right_high, right_sum)
            else:
                return (cross_low, cross_high, cross_sum)



x = list(map(int, input().split()))
a = list(map(int, input().split()))

b,c,d=ms(a,0,len(a)-1)
a=a[b:c+1]
p=0
for i in range(len(a)-1):
    for j in range(i+1,len(a)):
        p=p+(a[i]*a[j])
print(p)