#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;
using ll = long long;

ll limit = 1000000007;
ll modpow(ll x, ll n) {
  ll ans = 1;
  while(n > 0) {
    if(n % 2 == 1) {
      ans *= x;
      // ans %= MOD;
      if(ans > limit) {
        return -1;
      }
    }
    x *= x;
    // x %= MOD;
    if(x > limit) {
      return -1;
    }
    n >>= 1;
  }
  return ans;
}
int main() {
  int n;
  cin >> n;
  ll num = 1;
  vector<int> input(n);
  for(int i = 0; i < n; i++) {
    cin >> input[i];
  }
  for(int i = 0; i < n; i++) {
    ll tmp, a, cnt = 1;
    a = input[i];
    if(a < 2) {
      continue;
    }
    tmp = a;
    while(tmp--) {
      cnt *= (tmp + 1);
      if(num * modpow(a, cnt) > limit || modpow(a, cnt) == -1) {
        cout << limit << '\n';
        return 0;
      }
    }
    num *= modpow(a, cnt);
    if(num > limit) {
      cout << limit << '\n';
      return 0;
    } else if(num < 0) {
      cout << limit << '\n';
      return 0;
    }
  }
  if(limit % num == 0) {
    cout << -1 << '\n';
  } else {
    cout << limit % num << '\n';
  }
  return 0;
}