#include <bits/stdc++.h>

using i64 = long long;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);

    int n;
    std::cin >> n;

    std::vector<int> S;
    for (int i = 0; i < n; i++) {
        int d;
        std::cin >> d;

        S.emplace_back(d);
    }

    if (n == 10) {
        std::cout << -1 << "\n";
        return 0;
    }

    const int N = 1E7 + 1;
    std::vector<int> primes, minp(N);
    for (int i = 2; i < N; i++) {
        if (!minp[i]) {
            minp[i] = i;
            primes.emplace_back(i);
        }
        for (auto p : primes) {
            if (p * i > N) {
                break;
            }
            minp[i * p] = p;
            if (i % p == 0) {
                break;
            }
        }
    }

    for (auto &p : primes) {
        std::string s = std::to_string(p);

        bool ok = true;
        for (auto &d : S) {
            ok &= (std::count(s.begin(), s.end(), '0' + d) == 0);
        }
        if (ok) {
            std::cout << p << "\n";
            return 0;
        }
    }
    std::cout << -1 << "\n";

    return 0;
}