#include <algorithm>
#include <vector>
#include <stdio.h>
#include <iostream>
#include <cassert>
using namespace std;

#define ran(i, a, b) for ((i) = (a); (i) < (b); (i)++)
#define rep(i, a) ran ((i), 0, (a))
#define rep1(i, a) ran ((i), 1, (a)+1)
using ll = long long;
using vi = vector<int>;
using ii = pair<int, int>;
#if defined(SHIROKO1_LOCAL) && !defined(NDEBUG)
template <typename T>
static void DEBUG(T&& s) { cerr << s << endl; }
template <typename T, typename... Ts>
static void DEBUG(T&& a, Ts&&... as)
{
	cerr << a << ' ';
	DEBUG(as...);
}
#else
#define DEBUG(...) ((void)0)
#endif

static ll A[500100];
static int N;

int main()
{
	cin >> N;
	int i;
	rep (i, N)
		cin >> A[i];
	int l, r;
	ll ans = -(1LL<<60);
	rep (l, N) {
		ll v = 0;
		ll s = 0;
		ran (r, l, N) {
			v += s*A[r];
			s += A[r];
			ans = max(ans, v);
		}
	}
	cout << ans << endl;
	return 0;
}