package yukicoder;
import java.util.*;
public class Main{
	public static void main(String[] args)throws Exception{
		new Main().solve();
	}
	void solve(){
		Scanner sc=new Scanner(System.in);
		int[] d=new int[10];
		int n=sc.nextInt();
		for(int i=0;i<n;i++){
			d[sc.nextInt()]++;
		}
		boolean[] primeList=primeList(5000000);

		int memo[]=new int[10];
		int max=-1;
		//k...i
		for(int k=1,i=k;i<=5000000&&k<=5000000;i++){
			if(primeList[i]){
				int a=i;
				while(a>=1){
					memo[a%10]++;
					a/=10;
				}
			}
			if(check(d,memo)==-30){
				max=Math.max(i-k,max);
			}else if(check(d,memo)==-20){
				//継続して右側に進む
			}else if(check(d,memo)==-10){
				while(check(d,memo)==-10){
					if(primeList[k]){
						int b=k;
						while(b>=1){
							memo[b%10]--;
							b/=10;
						}
					}
					k++;
				}
			}
		}
		System.out.println(max);
	}
	boolean[] primeList(int n){
		boolean[] primeList=new boolean[n+1];
		Arrays.fill(primeList, true);
		primeList[0]=primeList[1]=false;
		for(int i=2;i<=n;i++){
			if(primeList[i]==true){
				for(int j=2;i*j<=n;j++){
					primeList[i*j]=false;
				}
			}
		}
		return primeList;
	}
	int check(int[] d,int[] memo){
		for(int i=0;i<10;i++){
			if(d[i]==1&&memo[i]==0)return -20;
			if(d[i]==0&&memo[i]>0)return -10;
		}
		return -30;
	}
	void tr(Object...o){System.out.println(Arrays.deepToString(o));}


}