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


class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int[] inpt = Reader.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();

        this.itemCount = inpt[0];

        int start = inpt[1];
        int flag = (1 << start);

        long ans = this.GetAns(start, flag, false);
        Console.WriteLine(ans);
    }

    private int itemCount;

    private long GetAns(int num, int flag, bool useDesc)
    {

        int max = (1 << (itemCount + 1)) - 2;

        if (max == flag)
        {
            if (useDesc)
            {
                return 1;
            } else {
                return 0;
            }
        }

        long ans = 0;

        if (useDesc)
        {
            for (int i = 1; i <= itemCount; i++)
            {
                int key = 1 << i;
                if ((flag & key) == 0)
                {
                    if (i > num)
                    {
                        ans++;
                    }
                    break;
                }
            }

        }
        else
        {
            for (int i = 1; i <= itemCount; i++)
            {
                int key = 1 << i;
                if ((flag & key) != 0)
                {
                    continue;
                }
                if (i < num)
                {
                    if (useDesc)
                    {
                        continue;
                    }
                    ans += this.GetAns(i, flag + key, true);
                }
                else
                {
                    ans += this.GetAns(i, flag + key, useDesc);
                }
            }
        }
        return ans;
    }

    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"





2 1






";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}