#include <iostream>

int factorial(int n) {
	if(n == 0 || n == 1)
		return 1;
	return n * factorial(n-1);
}
int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(NULL); 
	std::cout.tie(NULL);
	
	int n, k;
	
	std::cin >> n >> k;
	
	std::cout << factorial(n) / (factorial(n-k) * factorial(k)) << std::endl;
    
    return 0;
}