#include <bits/stdc++.h>

#define rep(i,s,n) for(int i = int(s); i < int(n); i++)
#define rrep(i,s,n) for(int i = int(n) - 1; i >= int(s); i--)
#define all(v) (v).begin(), (v).end()

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<class T>
bool chmin(T &a, T b) {
    if(a <= b) return false;
    a = b;
    return true;
}

template<class T>
bool chmax(T &a, T b) {
    if(a >= b) return false;
    a = b;
    return true;
}

using namespace std;

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

const int iinf = 1e9+7;

void jikken() {
    int n; cin >> n;
    vector<bool> a(1<<10,false);
    for (int p = 2; p <= n; p++){
        if (!is_prime(p)) continue;
        int s = 0;
        int x = p;
        while (x > 0){
            s |= (1<<(x%10));
            x /= 10;
        }
        a[(1<<10) - 1 - s] = true;
        //cout << p << " " << s << endl;
    }
    rep(i,0,10){
        rep(s,0,1<<10){
            if ((s >> i & 1) == 1){
                if (a[s]) a[s^(1<<i)] = true;
            }
        }
    }
    auto get = [](int s, int i){
        return s >> i & 1;
    };
    rep(s,0,1<<10){
        if (popcount((unsigned int)(s)) >= 9) continue;
        if (get(s,1) + get(s,2) + get(s,3) + get(s,5) + get(s,7) + get(s,9) == 6) continue;
        if (!a[s]) cout << s << " " << bitset<10>(s).to_string() << endl;
    }
}

int main(){
    auto get = [](int s, int i){
        return s >> i & 1;
    };
    int n; cin >> n;
    int s = 0;
    rep(i,0,n){
        int d; cin >> d;
        s ^= (1<<d);
    }
    for (int p = 2; p <= 1000; p++){
        if (!is_prime(p)) continue;
        int t = 0;
        int x = p;
        while (x > 0){
            t |= (1<<(x%10));
            x /= 10;
        }
        if (t & s) continue;
        cout << p << endl;
        return 0;
    }
    cout << -1 << endl;
    // bool ex1 = popcount((unsigned int)(s)) >= 9;
    // bool ex2 = get(s,1) + get(s,2) + get(s,3) + get(s,5) + get(s,7) + get(s,9) == 6;
    // bool ex3 = (s == 446 || s == 447 || s == 510);
    // if (ex1 || ex2 || ex3){
    //     cout << -1 << endl;
    //     return 0;
    // }
    // for (int p = 2; p <= 1000; p++){
    //     if (!is_prime(p)) continue;
    //     int t = 0;
    //     int x = p;
    //     while (x > 0){
    //         t |= (1<<(x%10));
    //         x /= 10;
    //     }
    //     if (t & s) continue;
    //     cout << p << endl;
    //     return 0;
    // }
}