import java.util.*;
class Cal{
int n;
int m;
public Cal(int n,int m) {
this.n=n;
this.m=m;
}
int getNum() {
int sum=1,t1=1,t2=1,t3=1;
int i;
for(i=n;i>=1;i--) {
t1*=i;
}
for(i=m;i>=1;i--) {
t2*=i;
}
for(i=n-m;i>=1;i--) {
t3*=i;
}
sum=t1/(t2*t3);
return sum;
}
}
public class Main{
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
while(sc.hasNext()) {
int a=sc.nextInt();
int b=sc.nextInt();
Cal cal=new Cal(a,b);
int sum=cal.getNum();
System.out.println(sum);
}
sc.close();
}
}