#include <bits/stdc++.h>

using namespace std;

long largestValue(vector <int> A) {
    vector <int> product;
    int i,j,k = 0;
    for (i = 0; i < A.size(); i++){
        for ( j = i+1; j < A.size(); j++)
        {
            product[k] = A[i]*A[j];
            k++;
        }
    }
   int max_so_far = 0, max_ending_here = 0;
   for ( i = 0; i < product.size(); i++)
   {
       max_ending_here = max_ending_here + product[i];
       if (max_ending_here < 0)
           max_ending_here = 0;
 
       else if (max_so_far < max_ending_here)
           max_so_far = max_ending_here;
   }
   return max_so_far;
}


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;
}