#include<bits/stdc++.h>
#define mp(x,y) make_pair((x),(y))
#define ll long long int
#define mem(x,y) memset(x,y,sizeof(x))
#define pb push_back
#define MOD (ll)(1e9+7)
#define N 100005
#define all(c) (c).begin(),(c).end()
#define lb lowe_bound
#define ub upper_bound
#define X first
#define Y second
#define f(i,a,b) for(int i=a;i<b;i++)
using namespace std;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
ll a[5*N+5],sum[5*N+5],sq[5*N+5];
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    cin>>n;

    f(i,0,n){
        cin>>a[i];
        if(i>0)sum[i]=a[i]+sum[i-1],sq[i]=a[i]*a[i]+sq[i-1];
        else sum[i]=a[i],sq[i]=a[i]*a[i];
    }
    ll ans=LONG_MIN,curr;
    for(int i=0;i<n;i++){
        for(int j=i;j<n;j++){
            if(i==0){
                curr = (sum[j]*sum[j]-sq[j]);
            }
            else curr = (((sum[j]-sum[i-1])*(sum[j]-sum[i-1]))-(sq[j]-sq[i-1]));
            ans = max(ans,curr);
        }
    }
    cout<<ans/2;

    return 0;
}