#include <bits/stdc++.h>
using namespace std;
#define sorted(a) sort(a.begin(), a.end());
typedef long long signed int ll;

bool isPrime(ll n) {
  if (n < 2) return false;
  else if (n == 2) return true;
  else if (n % 2 == 0) return false;

  double sqrtn = sqrt(n);
  for (int i = 3; i <= sqrtn; i += 2) {
    if (n % i == 0)
      return false;
  }
  return true;
}

int main(void) {
#ifdef DEBUG
  freopen("input.txt", "r", stdin);
#endif

  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int N;
  cin >> N;
  vector<int> A(N);
  for (int i = 0; i < N; i++) {
    cin >> A[i];
  }

  ll ans = -1;
  ll n;
  do {
    n = 0;
    for (int i = 0; i < N; i++) {
      n = n * pow(10, to_string(A[i]).length()) + A[i];
    }
    if (isPrime(n)) {
      ans = max(ans, n);
    }
  } while (next_permutation(A.begin(), A.end()));
  cout << ans << endl;

  return 0;
}