using System;
using System.Collections.Generic;

namespace No006_使いものにならないハッシュ
{
    class Program
    {
        static void Main()
        {
            int k = int.Parse(Console.ReadLine());
            int n = int.Parse(Console.ReadLine());
            bool[] numbers = new bool[n + 1];
            var prime = new List<int>();
            int start = 0, max = 0;

            if (k <= 2)
                prime.Add(2);

            for (int i = 3; i <= n; i += 2)
                numbers[i] = true;

            for (int i = 3; i < n; i += 2)
                for (int j = 2; i * j <= n; j++)
                    numbers[i * j] = false;

            for (int i = k + 1 - k % 2; i <= n; i += 2)
                if (numbers[i])
                    prime.Add(i);

            for (int i = 0; i < prime.Count - 1; i++)
            {
                bool[] checker = new bool[10];
                int count = 1;

                checker[hash(prime[i])] = true;
                for (int j = 1; j < 11 && i + j < prime.Count; j++)
                {
                    int value = hash(prime[i + j]);

                    if (!checker[value])
                    {
                        checker[value] = true;
                        count++;
                    }
                    else
                        break;
                }
                if (max <= count)
                {
                    max = count;
                    start = prime[i];
                }
            }

            Console.WriteLine(start);
        }

        static int hash(int number)
        {
            while (number >= 10)
                number = number / 10 + number % 10;

            return number;
        }
    }
}