#include <cstdio>

int f(int n, int k)
{
    if(k==1 || k==n)
            return 1;
    return f(n-1,k-1)+f(n-1,k);
}

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    printf("%d",f(n,k));
}