//---------------------------------------------------------------------------

#pragma hdrstop

//---------------------------------------------------------------------------

#pragma argsused
#include <iostream.h>
#include <iomanip.h>
int main(int argc, char* argv[])
{
  int m,n,i,k;
  double d;
  cin>>n>>m;
  cout<<setiosflags(ios::fixed)<<setprecision(0);
  while (n+m)
  {
    if (m==0)
      cout<<1;
    else
    {
      d=1;
      k=(n-m>m)?m:n-m;
      for (i=1;i<=k;i++)
      {  d*=n-i+1; d/=i; }
      cout<<d;
    }
    cout<<endl;
    cin>>n>>m;
  }
  return 0;
}
//---------------------------------------------------------------------------