#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vs = vector<string>;

const int INF = (1 << 30) - 1;
const ll INF64 = ((ll)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

const int dx[] = { -1, 0, 1, 0 };
const int dy[] = { 0, 1, 0, -1 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int res;

void dfs(int i, int n, int value, bool mode, vector<int>& v) {
	if (i == n) {
		res = max(res, value);
		return;
	}

	dfs(i + 1, n, value, false, v);
	if (!mode) {
		dfs(i + 1, n, value + v[i], true, v);
	}
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	int n;
	cin >> n;

	vector<int> v(n);
	for (int i = 0; i < n; i++) {
		cin >> v[i];
	}

	dfs(0, n, 0, false, v);
	cout << res << endl;
	return 0;
}