int C(int N, int K)
// ---------------------------------------------------
// Computes the number of groups of K out of N things.
// Precondition: N and K are nonnegative integers.
// Postcondition: Returns C(N, K).
// ---------------------------------------------------
{
   if ( (K == 0) || (K == N) )
      return 1;
   else if (K > N)
      return 0;
   else
      return C(N-1, K-1) + C(N-1, K);
}  // end C