#include <stdio.h>
#include <algorithm>
#include <vector>
#include <set>
using namespace std;
using lint = long long;

lint gcd(lint a, lint b)
{
	return b ? gcd(b,a%b) : a;
}

namespace miller_rabin{
	lint mul(lint x, lint y, lint mod){ return (__int128) x * y % mod; }
	lint ipow(lint x, lint y, lint p){
		lint ret = 1, piv = x % p;
		while(y){
			if(y&1) ret = mul(ret, piv, p);
			piv = mul(piv, piv, p);
			y >>= 1;
		}
		return ret;
	}
	bool miller_rabin(lint x, lint a){
		if(x % a == 0) return 0;
		lint d = x - 1;
			while(1){
				lint tmp = ipow(a, d, x);
				if(d&1) return (tmp != 1 && tmp != x-1);
				else if(tmp == x-1) return 0;
				d >>= 1;
			}
	}
	bool isprime(lint x){
		for(auto &i : {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37}){
			if(x == i) return 1;
			if(x > 40 && miller_rabin(x, i)) return 0;
		}
		if(x <= 40) return 0;
		return 1;
	}
}
namespace pollard_rho{
	lint f(lint x, lint n, lint c){
		return (c + miller_rabin::mul(x, x, n)) % n;
	}
	void rec(lint n, vector<lint> &v){
		if(n == 1) return;
		if(n % 2 == 0){
			v.push_back(2);
			rec(n/2, v);
			return;
		}
		if(miller_rabin::isprime(n)){
			v.push_back(n);
			return;
		}
		lint a, b, c;
		while(1){
			a = rand() % (n-2) + 2;
			b = a;
			c = rand() % 20 + 1;
			do{
				a = f(a, n, c);
				b = f(f(b, n, c), n, c);
			}while(gcd(abs(a-b), n) == 1);
			if(a != b) break;
		}
		lint x = gcd(abs(a-b), n);
		rec(x, v);
		rec(n/x, v);
	}
	vector<lint> factorize(lint n){
		vector<lint> ret;
		rec(n, ret);
		sort(ret.begin(), ret.end());
		return ret;
	}
};

int main()
{
	int N; scanf ("%d",&N);
	int A[10]; for (int i=0;i<N;i++) scanf ("%d",&A[i]);

	long long ans = -1;
	set<long long> chk;
	do{
		long long a = 0;
		for (int i=0;i<N;i++){
			if (A[i] < 10) a = a * 10 + A[i];
			else a = a * 100 + A[i];
		}
		if (chk.count(a)) continue;
		else{
			chk.insert(a);
			if (miller_rabin::isprime(a)) ans = max(ans,a);
		}
	}while(next_permutation(A,A+N));

	printf ("%lld\n",ans);
	return 0;
}