using System;
using System.Collections.Generic;
using System.Linq;

namespace No371_1{
    public class Program{
        public static void Main(string[] args){
            var sr = new StreamReader();
            //---------------------------------
            var l = sr.Next<long>();
            var h = sr.Next<long>();

            var pl = new List<int>();
            var tl = Enumerable.Range(2, (int)Math.Sqrt(h)).ToList();
            var sqrt = (int)Math.Sqrt(Math.Sqrt(h));
            while(tl[0] <= sqrt){
                var p = tl[0];
                pl.Add(p);
                tl.RemoveAll(x => x % p == 0);
            }
            pl.AddRange(tl);

            Func<long, int, bool> isAns = (i, j) =>{
                foreach(var p in pl.TakeWhile(x => x < j)){
                    if(i % p == 0) return false;
                }
                return true;
            };

            foreach(var p in pl.OrderByDescending(x => x)){
                for(var i = h + h % 2 - 1; i >= l; i -= 2){
                    if(i != p && i % p == 0 && isAns(i / p, p)){
                        Console.WriteLine(i);
                        return;
                    }
                }
            }

            Console.WriteLine(h - h % 2);
            //---------------------------------
        }
    }

    public class StreamReader{
        private readonly char[] _c = {' '};
        private int _index = -1;
        private string[] _input = new string[0];

        public T Next<T>(){
            if(_index == _input.Length - 1){
                _index = -1;
                while(true){
                    string rl = Console.ReadLine();
                    if(rl == null){
                        if(typeof(T).IsClass) return default(T);
                        return (T)typeof(T).GetField("MinValue").GetValue(null);
                    }
                    if(rl != ""){
                        _input = rl.Split(_c, StringSplitOptions.RemoveEmptyEntries);
                        break;
                    }
                }
            }
            return (T)Convert.ChangeType(_input[++_index], typeof(T), System.Globalization.CultureInfo.InvariantCulture);
        }
    }
}