2225.java

import java.util.*;

public class Main {

 public static void main(String[] args) {

 Scanner sc = new Scanner(System.in);

 int n = sc.nextInt();
 int k = sc.nextInt();
 int mod = 1000000000;

 int [][] d = new int[k+1][n+1];

 d[0][0] = 1;

 for(int i=1; i<k+1; i++) {
 for(int j=0; j<n+1; j++) {
 for(int x=0; x<=j; x++) {
 d[i][j] += d[i-1][j-x];
 d[i][j] %= mod;
 }
 }
 }

 System.out.println(d[k][n]);
 }
}