#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

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

    int n;
    cin >> n;

    ll ans = 1;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;

        if (a == 0) {
            ans = -1;
            break;
        } else if (a == 1) {
            continue;
        } else if (a >= 5) {
            ans = 1000000008;
            continue;
        }

        int hoge = 1;
        for (int i = 1; i < a + 1; i++) {
            hoge *= i;
        }

        for (int i = 0; i < hoge; i++) {
            if (a * ans > 1000000007) {
                ans = 1000000008;
                break;
            } else {
                ans *= a;
            }
        }
    }
    
    if (ans <= 0) cout << -1 << newl;
    else cout << 1000000007 % ans << newl;

    return 0;
}