/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.10.07 16:36:17
**/

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

long long 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;
}
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++;
	
	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 (MillerRabin(num)) ans = max(ans, num);
    } while (next_permutation(a.begin(), a.end()));
    cout << ans << endl;
    return 0;
}