#include <iostream>
#include <cmath>
#include <vector>
#include <ios>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#define lol long long
#define LIM 1000000007
using namespace std;

//const lol mod=1e9+7;

int main() {
    ios_base::sync_with_stdio(false);
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    lol n;
    cin >> n;
    lol x[n+1];
    lol cum[n+1],cum2[n+1];
    for(lol i=0; i<n; i++){
        cin >> x[i];
        if(i==0){
            cum[i]=x[i];
            cum2[i]=(x[i]*x[i]);
        }
        else{
            cum[i]=cum[i-1]+x[i];
            cum2[i]=cum2[i-1]+(x[i]*x[i]);
        }
    }
    lol ans=-LIM;
    for(lol i=0; i<n-1; i++){
        for(lol j=i+1; j<n; j++){
            lol t1,t2;
            if(i==0){
                t1=cum[j];
                t2=cum2[j];
            }
            else{
                t1=cum[j]-cum[i-1];
                t2=cum2[j]-cum2[i-1];
            }
            t1*=t1;
            lol cur=(t1-t2)/2;
            ans=max(ans,cur);
        }
    }
    cout << ans;
    return 0;
}