#include <bits/stdc++.h>
#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void(0)
#endif

using namespace std;

typedef long long ll;
#define all(x) begin(x), end(x)
constexpr int INF = (1 << 30) - 1;
constexpr long long IINF = (1LL << 60) - 1;
constexpr int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

template <class T> istream& operator>>(istream& is, vector<T>& v) {
    for (auto& x : v) is >> x;
    return is;
}

template <class T> ostream& operator<<(ostream& os, const vector<T>& v) {
    auto sep = "";
    for (const auto& x : v) os << exchange(sep, " ") << x;
    return os;
}

template <class T, class U = T> bool chmin(T& x, U&& y) { return y < x and (x = forward<U>(y), true); }

template <class T, class U = T> bool chmax(T& x, U&& y) { return x < y and (x = forward<U>(y), true); }

template <class T> void mkuni(vector<T>& v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <class T> int lwb(const vector<T>& v, const T& x) { return lower_bound(begin(v), end(v), x) - begin(v); }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin >> N;
    vector<int> Q(N);
    cin >> Q;

    vector pre(N + 1, vector<int>(2, -1));
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < 2; j++) pre[i + 1][j] = pre[i][j];
        pre[i + 1][Q[i] >= 0] = Q[i];
    }
    vector<ll> dp(2, -IINF), ndp(2, -IINF);
    for (int k = 0; k < N; k++) {
        for (int i = 0; i < 2; i++) {
            ll& val = dp[i];
            if (val == -IINF) continue;
            if (i == (Q[k] >= 0))
                chmax(ndp[i], val + 1LL * pre[k][i] * Q[k]);
            else
                chmax(ndp[i], val);
            chmax(ndp[Q[k] >= 0], val + 1LL * pre[k][i] * Q[k]);
            val = -IINF;
        }
        swap(dp, ndp);
        chmax(dp[Q[k] >= 0], 0);
    }

    ll ans = max(dp[0], dp[1]);
    cout << ans << '\n';
    return 0;
}