#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
#define ll long long

const int MAXN = (int) 2e5;

int v[MAXN + 1];

int main() {
    int n, i, j;
    ios::sync_with_stdio(false);
    cin >> n;
    for(i = 1; i <= n; i++) {
        cin >> v[i];
    }
    ll ans = -(1LL << 62);
    int cnt = 0;
    for(i = 1; i <= n; i++) {
        ll sum = 0, s = 0;
        for(j = i; j <= n; j++) {
            sum += 1LL * v[j] * s;
            s += v[j];
            cnt++;
            if(j > i) {
                ans = max(ans, sum);
                if(cnt > 4e8) {
                    cout << ans;
                    return 0;
                }
                 
            }
        }
    }
    cout << ans;
    return 0;
}