#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

const int N = 5e5 + 5;
int n, a[N], sum[N];
long long ans = 0;
int main() {
    cin >> n; sum[0] = 0;
    for(int i = 1; i <= n; i++){
        cin >> a[i]; sum[i] = sum[i - 1] + a[i];
    }
    for(int i = 1; i <= n - 1; i++)
           for(int j = i + 1; j <= n; j++){
               long long tmp = 0;
               for(int k = i; k <= j - 1; k++) tmp += a[k] * (sum[j] - sum[k]);
               ans = max(ans, tmp);
           }
    cout << ans;
    return 0;
}