#!/bin/env python3
n = int(input())
l = []
for i in range(n): l.append(int(input()))
ans = 0
for k in range(1, n):
    p = 0
    for i in range(0, k):
        p += l[i] * l[i]
    s = 0
    for i in range(k, n):
        s += l[i]
    ans = max(ans, p*s)
print(ans)