#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
typedef long long LL;

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n,x,y,s=0;
    cin>>n;
    int a[n];
    int max_sum=0,sum=0,sum1=0;
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
        sum+=a[i];
        if(sum>max_sum)
        {
            max_sum=sum;
            x=s;y=i;
        }
        
        if(sum<0)
        {
            sum=0;
            s=i+1;
        }
    } 
    for(int i=x;i<=y;i++)
    {
        for(int j=i+1;j<=y;j++)
        {
            sum1+=a[i]*a[j];
            //cout<<a[i]<<" "<<a[j]<<" ";
        }
    }
    cout<<sum1;
    return 0;
}