import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;
//BigInteger에 대해 공부하기
public class B_2407 {
    public static  void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n, m;
        StringTokenizer st = new StringTokenizer((br.readLine()));
        n = Integer.parseInt(st.nextToken());
        m = Integer.parseInt(st.nextToken());

        BigInteger[][] dp = new BigInteger[101][101];
        dp[1][0] = dp[1][1] = BigInteger.ONE;
        for(int i=0; i<101; i++){
            for(int j=0; j<=i; j++){
                if(i == j || j == 0){
                    dp[i][j] = BigInteger.ONE;
                }
                else{
                    dp[i][j] = dp[i-1][j].add(dp[i-1][j-1]);
                }
            }
        }
        System.out.println(dp[n][m]);
    }
}