#include <bits/stdc++.h>

using namespace std;

#define all(x) (x).begin(), (x).end()
using ll = long long;

bool is_prime(int x) {
    for (int i = 2; i * i <= x; i++) {
        if (x % i == 0) {
            return false;
        }
    }
    return true;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    vector<int> a(10);
    for (int i = 0; i < n; i++) {
        int d;
        cin >> d;
        a[d] = 1;
    }
    if (a[2] == 0) {
        cout << 2 << '\n';
    } else if (a[3] == 0) {
        cout << 3 << '\n';
    } else if (a[5] == 0) {
        cout << 5 << '\n';
    } else if (a[7] == 0) {
        cout << 7 << '\n';
    } else if (a[1] == 0) {
        cout << 11 << '\n';
    } else {
        if (a[9] == 1) {
            cout << -1 << '\n';
            return 0;
        }
        if (a[4] == 1 && a[8] == 1) {
            cout << -1 << '\n';
            return 0;
        }
        int ans = 1e9;
        function<void(int, int)> Dfs = [&](int t, int s) {
            if (s == (int) 1e7) {
                return;
            }
            if (is_prime(t)) {
                ans = min(ans, t);
                return;
            }
            for (int i = 0; i < 10; i++) {
                if (a[i]) {
                    continue;
                }
                Dfs(i * s + t, s * 10);
            }
        };
        Dfs(9, 10);
        cout << ans << '\n';
    }
    return 0;
}