#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void()
#endif

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  long long ans = 1;
  const int md = (int)1e9 + 7;
  auto fact = [](int n) {
    int ret = n;
    while (--n) ret *= n;
    return ret;
  };
  auto pow = [](int n, int p) {
    int ret = 1;
    while (p--) ret *= n;
    return ret;
  };
  while (n--) {
    int a;
    cin >> a;
    if (a >= 4) {
      cout << md << '\n';
      return 0;
    }
    ans *= pow(a, fact(a));
    if (ans == 0) {
      cout << -1 << '\n';
      return 0;
    }
    if (ans >= md) {
      cout << md << '\n';
      return 0;
    }
  }
  cout << md % ans << '\n';
  return 0;
}