What is the main idea of the passage?
When a person decides to get a dog, he or she has many kinds to choose from. As a rule, short-haired dogs are best for cities. Beagles, Boston Terriers, and Dachshunds make good city pets. Great Danes are short-haired, too. However, they are too big for city living. It is hard in a city to give them all the exercise they need. Setters, Springer Spaniels, and Collies are especially good as country dogs.