#include <bits/stdc++.h>

using namespace std;

long long i,j,ans,sum,a[1000009],ans1=-999999999999,d[1000009],x,y;
int main() {
    int n;
    cin >> n;
    d[0]=0;
  for(i=1;i<=n;i++)
  {
      cin>>a[i];
  d[i]=d[i-1]+a[i];
  } 
    sum=-99999999999;
    for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++)
        {
    if(d[j]-d[i-1]>sum){
        sum=d[j]-d[i-1];
        x=i;
        y=j;
    }
        }
    
    for(i=x;i<=y;i++)
        for(j=i+1;j<=y;j++)
        {
            sum=a[i]*a[j];
            ans+=sum;
        }
      if(ans>ans1)ans1=ans;   
     
      
    cout<<ans1<<endl;
    return 0;
}