#include <bits/stdc++.h>
using namespace std;

int main()
{
	auto is_prime = [](int64_t n) {
		if (n < 2)
		{
			return false;
		}
		for (int64_t i = 2; i * i <= n; i++)
		{
			if (n % i == 0)
			{
				return false;
			}
		}
		return true;
	};
	int n;
	cin >> n;
	vector<int> as(n);
	for (auto &a : as)
	{
		cin >> a;
	}
	sort(as.begin(), as.end());
	int64_t ans = -1;
	do
	{
		string s = ""s;
		for (auto &a : as)
		{
			s += to_string(a);
		}
		int64_t x = stoll(s);
		if (is_prime(x))
		{
			ans = max(ans, x);
		}
	} while (next_permutation(as.begin(), as.end()));
	cout << ans << endl;
	return 0;
}