#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main(void) {
    int N;
    cin >> N;
    int a;
    ll ans = 0;
    for (int i=0; i<N; i++) {
        cin >> a;
        if (ans <= 1 || (-1 <= a && a <= 1)) ans += abs(a);
        else ans *= a;
    }
    cout << ans << endl;
    return 0;
}