#include <bits/stdc++.h>
using namespace std;

#define ll long long int
#define M 1000000007

ll modexpo(ll base,ll expo,ll mod)
{
	ll result = 1;
	while(expo>0)
	{
		if(expo&1)result = (result*base)%mod;
		base = (base*base)%mod;
		expo = expo>>1;
	}
	return result;
}
int main ()
{
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	
	int n;
    cin >> n;
    vector<ll> ar(n+9,0),sm(n+9,0);
    for(int i=1;i<=n;i++)
    {
        ll x;
        cin >> x;
        ar[i] = x;
        sm[i] = sm[i-1]+ar[i];
    }
	ll ans = INT_MIN;
    for(int i=1;i<=n;i++)
    {
        for(int j=i+1;j<=n;j++)
        {
            ll ass = 0;
            for(int l = i;l<=j;l++)
            {
                for(int r = l+1;r<=j;r++)
                {
                    ass+=(ar[l]*ar[r]);
                }
            }
            ans = max(ans,ass);
        }
    }
    cout << ans;
	return 0;
}