import java.util.prefs.BackingStoreException;
import java.util.prefs.Preferences;

public class JI9032200 {

	public static void main(String[] args) throws BackingStoreException {
		Preferences userRoot = Preferences.userRoot(); 
		Preferences a = userRoot.node("a"); 
		System.out.println(a.nodeExists("a1")); 
		Preferences a1 = a.node("a1"); 
		System.out.println(a.nodeExists("a1"));
		a.flush(); 
		a1.removeNode(); 
		System.out.println(a.nodeExists("a1"));
	}

}