import java.util.TreeMap; public class Main { public static void main(String[] args) { TreeMap<String, String> capitalCities = new TreeMap<String, String>(); capitalCities.put("England", "London"); capitalCities.put("India", "New Dehli"); capitalCities.put("Austria", "Wien"); capitalCities.put("Norway", "Oslo"); capitalCities.put("Norway", "Oslo"); // Duplicate capitalCities.put("USA", "Washington DC"); System.out.println(capitalCities.size()); } }