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

const ll mod = 1000000007;

int main() {
    int N;
    cin >> N;
    ll A[N];
    bool flag = false;
    for (int i = 0; i < N; i++) {
        cin >> A[i];
        if (A[i] == 0) flag = true;
    }
    if (flag) {
        cout << "-1\n";
        return 0;
    }

    ll ans = 1;
    int cnt = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 1; j <= A[i]; j++) {
            for (int k = 1; k <= j; k++) {
                ans *= A[i];
                cnt++;
                if (ans > mod) goto out;
            }
        }
    }
    out:{}
    cout << (mod % ans) << "\n";
    return 0;
}