#include <stdio.h>
#include <stdlib.h>

int roundit ( double x )
{
   int r;               /* The rounded integer to return */
   double fpart;        /* Fractional part */

   /* Store in r the truncated value of |x| */
   r = (x >= 0) ? (int)x : (int)(-x);

   /* Compute the fractional part of |x| */
   fpart = (x >= 0) ? x - (double)r : -(x + (double)r);

   /* Modify r based upon fpart */
   if (fpart >= 0.5) ++r;

   /* Return r after sign adjustment */
   return (x > 0) ? r : -r;
}

unsigned int bincoeff ( unsigned int n, unsigned int r )
{
   double prod;

   if (r > n) return 0;

   /* Initialize empty product */
   prod = 1.0;

   while (r != 0) {
      prod *= (double)n / (double)r;
      --n; --r;
   }

   /* Return the rounded product */
   return roundit(prod);
}

int main ()
{
   // double x;
   unsigned int n, r;

   // printf("x = "); scanf("%lf", &x); printf("round(x) = %d\n", roundit(x));
   printf("n = "); scanf("%d", &n);
   printf("r = "); scanf("%d", &r);
   printf("C(n,r) = %d\n", bincoeff(n,r));

   exit(0);
}