#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using ll = long long;
#define SZ(v) (ll)((v).size())
#define pb emplace_back
#define AI(i) begin(i), end(i)
#define X first
#define Y second
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif

const int maxc = 1e7;
int sv[maxc];
vector<int> prs;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);

  for (int i = 2; i < maxc; i++) {
	  if (!sv[i]) {
		  prs.push_back(i);
	  }
	  for (int p : prs) {
		  if (p * i >= maxc) break;
		  sv[p * i] = true;
		  if (i % p == 0) break;
	  }
  }

  vector<int> mn(1 << 10, 1e9);
  for (int p : prs) {
	  int mask = 0;
	  for (char c : to_string(p))
		  mask |= 1 << (c - '0');
	  mn[mask] = min(mn[mask], p);
  }

  for (int i = 0; i < 10; i++)
	  for (int s = 0; s < 1 << 10; s++)
		  if (s >> i & 1)
			  mn[s] = min(mn[s], mn[s ^ (1 << i)]);

  /*
  for (int i = 0; i < 1 << 10; i++) {
	  if (mn[i] == int(1e9)) {
		  for (int j = 0; j < 10; j++)
			  if (i >> j & 1)
				  cout << j << ' ';
		  cout << endl;
	  }
  }
  */

  int n;
  cin >> n;
  int mask = 0;
  for (int i = 0; i < n; i++) {
	  int x;
	  cin >> x;
	  mask |= 1 << x;
  }
  int ans = mn[~mask & 1023];
  if (ans == int(1e9)) ans = -1;
  cout << ans << '\n';

  
  return 0;
}