#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <forward_list>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#ifdef RUTHEN_LOCAL
#include <debug.hpp>
#else
#define show(x) true
#endif

using namespace std;

#define REP(i, n) for (int i = 0; i < (n); i++)

vector<long long> divisor(long long n) {
    vector<long long> res;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            res.push_back(i);
            if (i * i != n) res.push_back(n / i);
        }
    }
    return res;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N;
    cin >> N;
    vector<int> cnt(10);
    REP(i, N) {
        int d;
        cin >> d;
        cnt[d]++;
    }
    const int INF = 1 << 30, M = 100000;
    vector<int> dp(1 << 10, INF);
    for (int i = 2; i < M; i++) {
        auto dv = divisor(i);
        if (dv.size() == 2) {
            int x = i, bit = 0;
            // cout << x << '\n';
            while (x > 0) {
                bit |= (1 << (x % 10));
                x /= 10;
            }
            REP(b, 1 << 10) {
                if ((b & bit) == 0) {
                    dp[b] = min(dp[b], i);
                }
            }
        }
    }
    int bit = 0;
    REP(i, 10) {
        if (cnt[i]) {
            bit |= 1 << i;
        }
    }
    int ans = dp[bit];
    if (ans == INF) ans = -1;
    cout << ans << '\n';
    return 0;
}