#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
const int MAX=5000000;
vector<ll> prime;
bool isprime[MAX];
void sieve(){
	for(ll i=3; i<MAX; i+=2){
		isprime[i]=1;
	}
	isprime[2]=1;
	prime.push_back(2);
	for(ll i=3; i<MAX; i++){
		if(isprime[i]){
			prime.push_back(i);
			for(ll j=2*i; j<MAX; j+=i){
				isprime[j]=0;
			}
		}
	}
	return;
}

int main()
{
    sieve();
	int n;
	cin>>n;
	ll a[9];
	for(int i=0; i<n; i++){
		cin>>a[i];
	}
	ll ans=-1;
	while(1){
		ll p10=1, p=0;
		for(int i=0; i<n; i++){
			p+=(p10*a[i]);
			if(a[i]>=10) p10*=100;
			else p10*=10;
		}
		if(p<MAX){
		    if(isprime[p]) ans=max(ans, p);
		}else{
		    for(int i=0; prime[i]*prime[i]<=p; i++){
		        if(p%prime[i]==0){
		          break;
		        }
	    	}
	    	ans=max(ans, p);
		}
		if(!next_permutation(a, a+n)) break;
	}
	cout<<ans<<endl;
	return 0;
}