#include <iostream>
using namespace std;

int fact(int x){                    // here fact is the name
    int f = 1;
    for(int i =1; i<=x; i++){
        f=f*i;
    }
    return f;
}
int main() {
    int n;
    cin>>n;
    int r;
    cin>>r;

    int a = fact(n);
    int b = fact(n-r);

    cout<<a/b;
}