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

namespace ASD_zad1_2
{
    class Program
    {
        class Newton
        {
            private int n;
            private int k;
            int licznik = 0;
            public Newton(int n, int k)
            {
                this.n = n;
                this.k = k;
            }
            public int SN4(int n, int m)
            {
                int[,] tab = new int[n,m];
                for (int i = 0; i < n; i++)
                {
                    tab[0,i] = 0;
                }
                for (int i = 0; i < m; i++)
                {
                    tab[i,0] = 1;
                }

                for (int i = 1; i < n-1; i++)
                {
                    for (int j = 1; j < m-1; j++)
                    {
                        tab[i,j] = tab[i - 1,j] + tab[i - 1,j - 1];
                        licznik++;
                    }
                }
                return tab[n,m];
            }
            public long SN2(int n, int k)
            {
                long wynikdlan = 1;
                long wynikdlak = 1;
                if (n - k > k)
                {
                    for (int i = 0; i < k; i++)
                    {
                        wynikdlan *= (n - i);
                    }
                    for (int l = 0; l < k; l++)
                    {
                        wynikdlak *= (k - l);
                    }
                    return wynikdlan / wynikdlak;

                }
                else
                {
                    for (int i = 0; i < n - k; i++)
                    {
                        wynikdlan *= (n - i);
                    }
                    for (int l = 0; l < n - k; l++)
                    {
                        wynikdlak *= (n - k - l);
                    }
                    return wynikdlan / wynikdlak;
                }
            }
        }
        static void Main(string[] args)
        {
            int n, k;
            String path = "C://inPP.txt";
            String path2 = "C://outPP.txt";
            StreamReader pathi = new StreamReader(path);
            String str = pathi.ReadLine();
            String[] tab = str.Split(' ');
            n = Int32.Parse(tab[0]);
            k = Int32.Parse(tab[1]);

            Newton niuton = new Newton(n, k);
            pathi.Close();

            StreamWriter patho = new StreamWriter(path2);
            int liczba = niuton.SN4(n, k);
            patho.WriteLine(liczba);
            patho.Close();
        }
    }
}