#include <bits/stdc++.h>

using namespace std;

int maxSubArraySum(vector <int> a, int size)
{
    int max_so_far = INT_MIN, max_ending_here = 0,start=0,end=0,s=0;
 
    for (int i=0; i< size; i++ )
    {
        max_ending_here += a[i];
 
        if (max_so_far < max_ending_here)
        {
            max_so_far = max_ending_here;
            start = s;
            end = i;
        }
 
        if (max_ending_here < 0)
        {
            max_ending_here = 0;
            s = i + 1;
        }
    }
    int khamar = 0;
    for(int i=start;i<end;i++)
    {
        for(int j=i+1;j<end+1;j++)
        {
            khamar+=a[i]*a[j];
        }
    }
    return khamar;
}

long largestValue(vector <int> A,int n) {
    
    return maxSubArraySum(A,n);
    // Return the largest value of any of A's nonempty subarrays.
}

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,n);
    cout << result << endl;
    return 0;
}