#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
#define FastIO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define pb push_back
#define mp make_pair
#define F first
#define S second

const int inf = 2147483647;
const int MOD = 1e9+7;
const int MAXN = 1e5+9;

long largestValue(vector <int> A) {
    ll sum=0;
    for (int i = 0; i < A.size(); ++i) {
        ll t=A[i],p=0;
        for (int j = i+1; j < A.size(); ++j) {
            p+= t*A[j];
            t+= A[j];
            sum = max(sum,p);
        }
    }
    return sum;
}

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;
}