#include <bits/stdc++.h>
#include <math.h>

#include <algorithm>
#include <array>
#include <atcoder/all>
#include <bitset>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <sstream>
#include <vector>

using namespace std;
using namespace atcoder;

using Graph = vector<vector<int>>;

using ll = long long;
typedef pair<ll, ll> P_ll;
typedef pair<int, int> P;

const ll INF_ll = 1e17;
const int INF = 1e8;
template <class T>
bool chmax(T& a, const T& b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T& a, const T& b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T>
using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
const ll MOD = 1e9 + 7;
int main() {
  int N;
  cin >> N;
  vector<ll> A(N);
  for (int i = 0; i < N; i++) {
    cin >> A[i];
  }
  for (int i = 0; i < N; i++) {
    if (A[i] == 0) {
      cout << -1 << endl;
      return 0;
    }
  }
  for (int i = 0; i < N; i++) {
    if (A[i] >= 4) {
      cout << MOD << endl;
      return 0;
    }
  }
  ll now = 1;
  const int d[] = {1, 1, 2, 6};
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < d[A[i]]; j++) {
      now *= A[i];
      if (now > MOD) {
        cout << MOD << endl;
        return 0;
      }
    }
  }
  cout << MOD % now << endl;

  return 0;
}