import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int[] a = new int[n];
    for(int i = 0; i < n; i++) {
      a[i] = sc.nextInt();
    }
    int[] A = new int[10];
    for(int i = 0; i < n; i++) {
      A[a[i]] = 1;
    }
    int ans = -1;
    ArrayList<Integer> prime = new ArrayList<Integer>();
    boolean[] is_prime = new boolean[5000001];
    for(int i = 0; i <= 5000000; i++) is_prime[i] = true;
    is_prime[0] = false;
    is_prime[1] = false;
    for(int i = 2; i <= 5000000; i++) {
      if(is_prime[i]) {
        prime.add((int)i);
        for(int j = 2 * i; j <= 5000000; j += i) is_prime[j] = false;
      }
    }
    int[] P = new int[5000001];
    for(int i = 0; i < prime.size(); i++) {
      P[prime.get(i)] = 1;
    }
    int p = 1;
    for(int i = 1; i <= 5000000; i++) {
      int[] keta = new int[10];
      int t = 0;
      for(int j = p; j <= 5000000; j++) {
        if(P[j] == 1) {
          String str = String.valueOf(j);
          for(int k = 0; k < str.length(); k++) {
            int sk = Integer.parseInt(String.valueOf(str.charAt(k)));
            keta[sk]++;
          }
          int c = 2;
          for(int k = 0; k < 10; k++) {
            if(A[k] == 1) {
              if(keta[k] == 0) c = Math.min(c, 1);
            } else { 
              if(keta[k] == 0) c = Math.min(c, -1);
            }
          }
          if(c == 2) {
            ans = Math.max(ans, j - i + 1);
          } else if(c == 1) {
            
          } else {
            p = Math.max(i + 1, j);
            break;
          }
        }
      } 
    }
    System.out.println(ans);
  }
}