/***

***/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
int main()
{
	int n;
	cin >> n;
	ll A[n + 1];
	A[0] = 0;
	for (int i = 1; i <= n; i++)
	{
		cin >> A[i];
	}
	ll sum[n + 1];
	ll el2[n + 1];
	sum[0] = 0;
	el2[0] = 0;
	for (int i = 1; i <= n; i++)
	{
		sum[i] = sum[i - 1] + A[i];
		el2[i] = el2[i - 1] + A[i] * A[i];
	}
	ll ans = -1e16;
	for (int r = 1; r <= n; r++)
	{
		if (sum[r]*sum[r] > ans)
			for (int l = 1; l <= r; l++)
			{
				ans = max(ans, (sum[r] - sum[l - 1]) * (sum[r] - sum[l - 1]) - el2[r] + el2[l - 1]);
			}
	}
	cout << ans / 2 << endl;
}