/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.10.07 16:40:58
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

bool MillerRabin(long long v, int loop = 10) {
    long long d = v - 1;
    int s = 0, i, j;
    if (v <= 1) return false;
    if (v == 2) return true;
    if (v % 2 == 0) return false;
    while (d % 2 == 0) d /= 2, s++;
    auto modpow = [](__int128_t a, long long n, long long mo) {
        __int128_t r = 1;
        a %= mo;
        while (n) r = r * ((n % 2) ? a : 1) % mo, a = a * a % mo, n >>= 1;
        return r;
    };
    for (i = 0; i < loop; i++) {
        ll a = abs(1LL * rand() * rand() + rand()) % (v - 2) + 1;
        ll r = modpow(a, d, v);
        if (r == 1 || r == v - 1) continue;
        for (j = 0; j < s; j++) {
            r = modpow(r, 2, v);
            if (r == v - 1) break;
        }
        if (j == s) return false;
    }
    return true;
}
int main() {
    int n;
    cin >> n;
    vector< int > a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    ll ans = -1;
    do {
        ll num = 0;
        for (int i = 0; i < n; i++) {
            if (a[i] >= 10) {
                num *= 100;
                num += a[i];
            } else {
                num *= 10;
                num += a[i];
            }
        }
        
        if (ans < num && MillerRabin(num)) ans = max(ans, num);
    } while (next_permutation(a.begin(), a.end()));
    cout << ans << endl;
    return 0;
}