using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using Enu = System.Linq.Enumerable;

class Program
{
    static readonly int MaxR = (int)5e6;

    void Solve()
    {
        int N = reader.Int();
        var A = reader.IntArray(N).OrderBy(a => a).ToArray();
        bool[] available = Enu.Range(0, 10).Select(i => A.Contains(i)).ToArray();
        var prime = Sieve(MaxR);
        int L = 1, R = 1;
        var used = new HashSet<int>();
        int ans = -1;

        Predicate<int> OK = p =>
        {
            if (!prime[p]) return true;
            int t = p;
            while (t > 0)
            {
                if (!available[t % 10]) return false;
                t /= 10;
            }
            while (p > 0) { used.Add(p % 10); p /= 10; }
            return true;
        };

        while (R <= MaxR)
        {
            if (OK(R))
            {
                if (used.Count == A.Length) ans = Math.Max(ans, R - L);
                R++;
            }
            else
            {
                L = ++R;
                used.Clear();
            }
        }

        Console.WriteLine(ans);
    }


    static bool[] Sieve(int n)
    {
        bool[] primes = new bool[n + 1];
        bool[] composite = new bool[n + 1];
        for (int i = 2; i <= n; i++)
        {
            if (composite[i]) continue;
            primes[i] = true;
            for (int j = i + i; j <= n; j += i) composite[j] = true;
        }
        return primes;
    }




    Reader reader = new Reader(Console.In);
    static void Main() { new Program().Solve(); }
}

class Reader
{
    private readonly TextReader reader;
    private readonly char[] separator = { ' ' };
    private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
    private string[] A = new string[0];
    private int i;

    public Reader(TextReader r) { reader = r; }
    public bool HasNext() { return Enqueue(); }
    public string String() { return Dequeue(); }
    public int Int() { return int.Parse(Dequeue()); }
    public long Long() { return long.Parse(Dequeue()); }
    public double Double() { return double.Parse(Dequeue()); }
    public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
    public int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public int[][] IntGrid(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public string Line() { return reader.ReadLine().Trim(); }
    private string[] Split(string s) { return s.Split(separator, removeOp); }
    private bool Enqueue()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return Enqueue();
        A = Split(line);
        i = 0;
        return true;
    }
    private string Dequeue() { Enqueue(); return A[i++]; }
}