#include <stdio.h>
#include <bits/stdc++.h>			

#define pb push_back
#define pf push_front
#define pp pop_back
#define sz(a) (int)(a.size())
#define mp make_pair
#define F first
#define S second
#define next _next
#define prev _prev
#define left _left
#define right _right
#define y1 _y1
#define all(x) x.begin(), x.end()
#define what_is(x) #x << " is " << (x)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int N = (int)1e6 + 123;
const ll INF = (ll)1e18 + 123;
const int inf = (int)1e9 + 123;
const int MOD = (int)1e9 + 7;

void megaRandom() {
	unsigned int FOR;
 	asm("rdtsc" : "=A"(FOR));
  srand(FOR);
}

int n, a[N];

int main() {
	megaRandom();
	cin >> n;
	for(int i = 1; i <= n; i ++) {
		cin >> a[i];
	}
	ll mx = 0;
	for(int i = 1; i <= n; i ++) {
		int sum = 0;
		ll cost = 0;
		for(int j = i; j <= n; j ++) {
			cost += 1ll * sum * a[j];
			sum += a[j];
			
            mx = max(mx, cost);
		}
	}
	cout << mx;
	return 0;  
}