#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
const ll mod = int(1e9) + 7;

int main() {
    ll N;
    cin >> N;
    vector<ll> a(N);
    rep(i, N) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    if (a[0] == 0) {
        cout << -1 << endl;
        return 0;
    }
    ll ans = 1;
    rep(i, N) {
        if (a[i] >= 4) {
            cout << mod << endl;
            return 0;
        }
        ll div = 1;
        rep(j, a[i]) {
            div *= (j + 1);
        }
        // cerr << "div" << div << endl;
        rep(j, div) {
            ans *= a[i];
            if (ans > (mod)) {
                break;
            }
        }
    }
    cout << mod % ans << endl;
    return 0;
}