using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace YukiCoderCS
{
    class Program
    {
        static void Main(string[] args) => new Program().Solve();
        void Solve()
        {
            var t = Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray();
            var N = t[0];
            var K = t[1];
            var ans =
                N < K
                ? 0
                : (int)Math.Pow(2, (N - K));
            Console.WriteLine(ans);
        }
    }
}