#include <map>
#include <set>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <cstdio>
#include <vector>
#include <cstdlib>
#include <iostream>
#include <algorithm>

#define pb push_back

using namespace std;

const int N = (int) 3e5 + 7;
const int MOD = (int) 1e9 + 7;

int n;
int a[N];

long long s[N];
long long p[N];

int main() {
  #ifdef LOCAL
  freopen("in.txt", "r", stdin);
  #endif
  ios_base::sync_with_stdio(0);


  cin >> n;
  for (int i = 1; i <= n; i++) {
  	cin >> a[i];
  	s[i] = s[i - 1] + a[i];
  	p[i] = p[i - 1] + a[i] * 1ll * a[i];
  }
  long long ans = 0;
  for (int l = 0; l < n; l++) {
  	for (int r = l + 1; r <= n; r++) {
  		ans = max(ans, (s[r] - s[l]) * (s[r] - s[l]) - (p[r] - p[l]));
  		//cout << l << ' ' << r << ' ' << (s[r] - s[l]) * (s[r] - s[l]) - (p[r] - p[l]) << endl;
  	}
  }
  cout << ans / 2;
  return 0;
}