1 import java.io.BufferedReader;
 2 import java.io.IOException;
 3 import java.io.InputStreamReader;
 4 
 5 public class Main {
 6     public static void main(String[] args) throws IOException{
 7         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 8         String[] str = br.readLine().split(" ");
 9         int m = Integer.parseInt(str[0]);
10         int n = Integer.parseInt(str[1]);
11         
12         int coefficient = binomialCoe(m,n);
13         
14         System.out.println(coefficient);
15     }
16 
17     private static int binomialCoe(int k, int n) {
18         if( k == 0 || k ==n)
19             return 1;
20         return binomialCoe( k , n-1 ) + binomialCoe( k-1 , n-1 );
21     }
22 }