#include <stdio.h>
/* Define rabbits function */
int rabbits (int n) {
  if (n == 0 || n == 1)
     return 1;
   else return rabbits (n - 1) + rabbits (n - 2);
}
/* Test rabbits function */
main ( ) {
  printf ("At the end of month 1, there is %i.\n", rabbits (1));
  printf ("At the end of month 10, there are %i.\n", rabbits (10));
  printf ("At the end of month 20, there are %i.\n", rabbits (20));
}