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

ll p[]={2,3,5,7,11,13,17,19,23};ll sqa(ll a,ll b,ll c){ll ret = 1;while(b){if(b&1)ret=(__int128)ret*a%c;a=(__int128)a*a%c;b>>=1;}return ret;}bool ML(ll x){if(x==2)return true;if(x<2||!(x&1))return false;ll y = x-1;int s = 0;while((y&1)==0)y>>=1,s++;for(ll c :p){if(c>=x)return true;ll d = sqa(c,y,x);if(d==1)continue;for(int j=0;j<s;j++){ll t = (__int128)d*d%x;if(t==1 && d!=1 && d!=x-1)return false;d = t;}if(d!=1)return false;}return true;}ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}ll div(ll x){ll a=rand()%(x-1)+1,b=a,i=1,k=2;ll c=1;do{i++;ll d = gcd(b-a+x,x);if(d!=1 && d!=x)return d;if(i==k)b=a,k<<=1;a=((__int128)a*a+x-c)%x;}while(a!=b);return x;}

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 (ML(a)) ans = max(ans,a);
		}
	}while(next_permutation(A,A+N));

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