#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int main() {
    long n;
    long max_so_far = -99999999, max_ending_here = 0;
    long start=0,end=0,s=0,sum=0;
    cin>>n;
    long a[n];
    for(long i=0;i<n;i++)
    {
        cin>>a[i];
    }
     for (long i=0; i< n; 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;
        }
    }
    for(long i=start;i<end;i++)
    {
        for(long j=i+1;j<=end;j++)
        {
            sum=sum+a[i]*a[j];
        }
    }
    cout<<sum;
    return 0;
}