#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

ll largestValue(vector <int> A) {
    ll res = 0;
    for (int i = 0; i < A.size(); i++) {
        ll cur = 0, sum = 0;
        for (int j = i; j < A.size(); j++) {
            cur += sum * A[j]; sum += A[j];
            res = max(res, cur);
        }
    }
    return res;
}

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