#include <bits/stdc++.h>

using namespace std;
#define ll long long

long largestValue(vector <int> A) {
    // Return the largest value of any of A's nonempty subarrays.
    ll s=0;
    for( int j =0;j<A.size();j++){
        ll in=A[j],var=0;
        for(int i=j+1;i<A.size();i++){
            var+=in*A[i];
            in+=A[i];
            s=max(s,var);
        }
    }
    return s;
}

int main() {
    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;
}