#include<iostream>
#include<climits>
using namespace std;
 
int maxSubArraySum(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;
        }
    }
   // cout << "Maximum contiguous sum is "
    //    << max_so_far << endl;
    //cout << "Starting index "<< start
     //   << endl << "Ending index "<< end << endl;
    long int i,j,sum=0;
    for(i=start;i<=end-1;i++){
        for(j=i+1;j<=end;j++){
            sum+=a[i]*a[j];
        }
    }
    cout<<sum;
    return 0;
}
 
/*Driver program to test maxSubArraySum*/
int main()
{
    int n,a[1000000];
    cin>>n;
    int i;
    for(i=0;i<n;i++)
        cin>>a[i];
     int max_sum = maxSubArraySum(a, n);
    return 0;
}