#include <stdio.h>
/* Function prototype for rabbits function */
int rabbits (int);
/* Function definitions requiring rabbits function prototype */
int previous_month (int n) {return rabbits (n - 1);}
int penultimate_month (int n) {return rabbits (n - 2);}
/* Function definition for rabbits function */
int rabbits (int n) {
  if (n == 0 || n == 1)
     return 1;
   else return previous_month (n) + penultimate_month (n);
}
/* Test rabbits function */
main ( ) {
  printf ("At the end of month 1, there is %i.\n", rabbits (1));
  printf ("At the end of month 2, there are %i.\n", rabbits (2));
  printf ("At the end of month 3, there are %i.\n", rabbits (3));
}