#include <stdio.h>

int combinacao(int n, int k){
	
	if (k > n){
		return 0;
	}
	
	int fatorial_n = 1, fatorial_k = 1, fatorial_nk = 1;
	
	for(int i = 1; i <= n; i++){
		fatorial_n *= i;	
	}
	for(int j = 1; j <= k; j++){
		fatorial_k *= j;
	}
	for(int w = 1; w <= (n-k); w++){
		fatorial_nk *= w;
	}
		
	return fatorial_n / (fatorial_k * fatorial_nk);
}

int main(void){
	
	int n, k;
	scanf("%d %d", &n, &k);	
	printf("%d\n", combinacao(n, k));
	return 0;	
}