#include <bits/stdc++.h>

#ifndef ONLINE_JUDGE

#include "template.cpp.h"

#else
#define debug(...)
#endif
#define int long long
using namespace std;
#define cinv(v) for (auto &it:v) cin>>it;
#define coutv(v) for (auto &it:v) cout<< it<<" "; cout<<'\n';

const int N = 5e6;
vector<bool> is_prime(N, true);
vector<int> prime;
bool has[10];

void shelby() {
    int n;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        int x;
        cin >> x;
        has[x] = true;
    }
    for (auto &it: prime) {
        int tmp = it;
        bool f = true;
        while (tmp) {
            if (has[tmp % 10]) {
                f = false;
                break;
            }
            tmp /= 10;
        }
        if (f) {
            cout << it << '\n';
            return;
        }
    }
    cout << "-1\n";
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    is_prime[0] = is_prime[1] = false;
    for (int i = 2; i < N; i++) {
        if (is_prime[i]) {
            prime.push_back(i);
            for (int j = i * i; j < N; j += i)
                is_prime[j] = false;
        }
    }
    int t = 1;
//    cin >> t;
    for (int _ = 1; _ <= t; ++_) {
//        cout << "Case " << _ << ": ";
        shelby();
    }
}