Exercise

## 9.6 Exercise

1. Consider the “farm” problem in section 9.5. (Source code may be found in `farm.ecl`, if you have access to it.) Try running this program to find the answer. Note that other, larger solutions are available by selecting more.
   This implementation sums three integer variables (`FA`, `FB` and `FC`), and then constrains their order to remove symmetries. Would this be a good candidate for the global constraint `ordered_sum/2`? Modify the program so that it does use `ordered_sum/2`. How does the run time compare with the original?