#include <bits/stdc++.h>

using namespace std;

long largestValue(vector <int> A) {
    return -1;
}

void maxSubArraySum(int a[], int size);
int main() {
    int n;
    cin >> n;
    vector<int> A(n);
    for(int A_i = 0; A_i < n; A_i++){
       cin >> A[A_i];
    }
    
    int array[n] = {0};
    for(int i = 0; i < n; i++)
        array[i] = A[i];
    
    long result = largestValue(A);
   // cout << result << endl;
    
    maxSubArraySum(array, n);
    
    return 0;
}

void maxSubArraySum(int array[], 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 += array[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;
        }
    }
    long long cxValue = 0;
    for(int i = start; i <= end; i++){
        for(int j = i+1; j <= end; j++){
          //  cout << array[i] * array[j] << endl << endl;
            cxValue = cxValue + ( array[i] * array[j]);
        }
    }
    cout << cxValue << endl;
   
}