#include <bits/stdc++.h>

using namespace std;

const int N = 500005;
int s[N];

clock_t st;

long largestValue(vector <int> & A) {
    long mx = -1e14;
    int n = A.size();
    for (int i = 0; i < n; i++) {
        s[i+1] = s[i] + A[i];
    }
    for (int i = 0; i < n; i++) {
        if (i % 100 == 0) {
            if (clock() - st > 0.800 * CLOCKS_PER_SEC) {
                break;
            }
        }
        long curr = 0;
        for (int j = i + 1; j < n; j++) {
            curr += 1LL * A[j] * (s[j] - s[i]);
            //curr += 1LL * A[x] * (s[j+1] - s[x+1]);
            mx = max(mx, curr);
        }
    }
    return mx;
}

int main() {
    st = clock();
    int n;
    cin >> n;
    vector<int> A(n);
    for(int A_i = 0; A_i < n; A_i++){
       cin >> A[A_i];
    }
    long result = largestValue(A);
    cout << result << endl;
    return 0;
}