#include <stdio.h>
int main()
{
int N, K, n1=1, nk1=1, k1=1;
scanf_s("%d %d", &N, &K);
for (int i = N; i >= 1; i--)
{
n1 *= i;
}
for (int i = N-K; i >= 1; i--)
{
nk1 *= i;
}
for (int i = K; i >= 1; i--)
{
k1 *= i;
}
printf("%d\n", n1 / (nk1 * k1));
return 0;
}