#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define LL long long
#define st first
#define nd second
#define endl '\n'
using namespace std;

const int MAXN = 500005, lg = 10;
bool pr[MAXN];
int vis[1 << lg], inf = 1e9;

int get_digits(int x) {
  int ret = 0;
  while(x) {
    ret |= 1 << (x % 10);
    x /= 10;
  }
  return ret;
}

int main() {

  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int bmask;
  for(int i = 0; i < (1 << lg); ++i) {
    vis[i] = inf;
  }
  for(int i = 2; i < MAXN; ++i) {
    if(!pr[i]) {
      bmask = get_digits(i);
      vis[bmask] = min(i, vis[bmask]);
      for(LL j = 1LL * i * i; j < MAXN; j += i) {
        pr[j] = 1;
      }
    }
  }

  for(int i = 0; i < (1 << lg); ++i) {
    for(int j = 0; j < lg; ++j) {
      vis[i | (1 << j)] = min(vis[i | (1 << j)], vis[i]);
    }
  }
  int n, d;
  cin >> n;
  int cur = (1 << lg) - 1;
  while(n--) {
    cin >> d;
    cur ^= (1 << d);
  }
  if(vis[cur] == inf) {
    cout << -1 << endl;
  }
  else cout << vis[cur] << endl;

}