#include
#include
int fact (int n);
int main ()
{
int m,k;
scanf("%d %d",&k,&m);
printf("%d",fact(m)/(fact(k)*fact(m-k)));
}
int fact(int n)
{
int i;
int p;
i=(int)n;
p=1;
for(;i>=1;i--)
{
p=i*p;
}return p;
}