#include <bits/stdc++.h>

using namespace std;


using ll = long long;

#define flt double
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define rep(i, n) for(int i = 0; i < n; i += 1)
#define len(a) ((int)(a).size())


const ll inf = 1e18;
mt19937 rnd(234);


const int maxn = 1e7;
char is_prime[maxn + 1];
vector<int> primes;

int32_t main() {
    if (1) {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout.tie(0);
    }
    for (int i = 2; i <= maxn; i += 1) {
        is_prime[i] = true;
    }
    primes.clear();
    for (int i = 2; i <= maxn; i += 1) {
        if (is_prime[i]) {
            primes.push_back(i);
            for (int j = 2 * i; j <= maxn; j += i) {
                is_prime[j] = false;
            }
        }
    }
    int n;
    cin >> n;
    int is_bad[10];
    rep(i, 10) is_bad[i] = false;
    rep(i, n) {
        int x;
        cin >> x;
        is_bad[x] = true;
    }
    for (auto p : primes) {
        bool ok = true;
        ll f = p;
        while (f > 0) {
            if (is_bad[f % 10]) {
                ok = false;
                break;
            }
            f /= 10;
        }
        if (ok) {
            cout << p << "\n";
            return 0;
        }
    }
    cout << -1 << "\n";
    return 0;
}